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Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 1:

Eigenvalues of the Matrix

[\begin{matrix} 3 & - 1 & - 1 \\ - 1 & 3 & - 1 \\ - 1 & - 1 & 3 \end{matrix}] a r e

1,1,1

1,1,2

1,4,4

1,2,4

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 2:

The solution of the differential equation

\frac{d^{2} y}{d x^{2}} - \frac{d y}{d x} - 2 y = 3 e^{2 x},

where,y(0)=0 and y'(0)=-2 is

A	$y = e^{- x} - e^{2 x} + x e^{2 x}$	B	$y = e^{x} - e^{- 2 x} - x e^{2 x}$
C	$y = e^{- x} + e^{2 x} + x e^{2 x}$	D	$y = e^{x} - e^{- 2 x} + x e^{2 x}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 3:

If Z=

e^{a x + b y}

F(ax-by); the value of

b . \frac{\partial Z}{\partial x} + a \frac{\partial Z}{\partial y} i s

2abZ

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 4:

The general integral of the partial differential equation

y^{2} p - x y q = x (z - 2 y) i s

A	$ϕ (x^{2} + y^{2}, y^{2} - y z) = 0$	B	$ϕ (x^{2} - y^{2}, y^{2} + y z) = 0$
C	$ϕ (x y, y z) = 0$	D	$ϕ (x + y, I n x - z) = 0$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 5:

\frac{d^{2} y}{d t^{2}} + y = 0

under the conditions

y = 1, \frac{d y}{d t} = 0, w h e n t = 0,

then y is equal to

sin t

cos t

tan t

cot t

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 6:

If the system 2x-y+3z=2 x+y+2z=2 5x-y+az=b has infinitely many solutions, then the values of and b, respectively,are

-8and 6

8 and 6

-8 and 6

8 and -6

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 7:

Evaluate

\oint \frac{1}{c {(z - 1)}^{3} . (z - 3)} d z

where c is the rectangular region defined by x=0,x=4,y=-1and y=1

A	1	B	0
C	$\frac{π}{2} i$	D	$π (3 + 2 i)$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 8:

The Fourier Transform of e

- \frac{x^{2}}{2} i s

A	$\frac{1}{2} . e^{- \frac{w^{2}}{2}}$	B	$e^{- \frac{w^{2}}{2}}$
C	$\frac{π}{2}$	D	$\sqrt{π}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 9:

In a sample of 100 students, the mean of the marks (only integers)obtained by them in a test is 14 with its standard deviation of 2.5(marks obtained can be fitted with a normal distribution). The percentage of students scoring 16 marks is (Area under standard normal curve between z=0 and z=0.6is 0.22567;and between z=0 and z=1.0 is 0.3413)

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 10:

Consider a random variable to which a Poisson distribution is best fitted. It happens that

P_{(X = 1)} = \frac{2}{3} P_{(x = 2)}

on this distribution plot. The variance of this distribution will be

A	3	B	3
C	1	D	$\frac{2}{3}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 11:

In Face-centered Cubic structure (FCC), what a number of atoms is present in each unit cell?

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 12:

If (n) is lattice points per units cell of the cubic system,(N) and (M) are the Avogadro's number and atomic weight, respectively, and (p) is the density of the element, them the lattice constant(a) is

A	${(\frac{M p}{n N})}^{\frac{1}{3}}$	B	${(\frac{N M}{n p})}^{\frac{1}{3}}$
C	${(\frac{n M}{N p})}^{\frac{1}{3}}$	D	${(\frac{N p}{n M})}^{\frac{1}{3}}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 13:

The magnetic susceptibility of aluminium is

2.1 \times 10^{- 5}

. The permeability and relative permeability are, respectively

A	$12.6 \times 10^{- 7} a n d 1.0021$	B	$1.26 \times 10^{- 7} a n d 1.0021$
C	$12.6 \times 10^{- 7} a n d 1.000021$	D	$1.26 \times 10^{- 7} a n d 1.000021$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 14:

An iron rod of

10^{- 3} m^{3}

volume and relative permeability of 1150 is placed inside a solenoid wound with 5turns/cm. If a current of 0.5 A is allowed to pass through the solenoid, the magnetic of the rod is

A	$2.87 \times 10^{4} A . m^{2}$	B	$28.7 \times 10^{3} A . m^{2}$
C	$2.87 \times 10^{2} A . m^{2}$	D	$28.7 \times 10^{2} A . m^{2}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 15:

When an alternating voltage of a given frequency is applied to a dielectric material, dissipation of energy occurs due to

Continual change in the orbital paths of the electrons in the atomic structure
A small conduction current through the dielectric
Eddy currents

Which of the above statements are correct?

1,2 and 3

1 and 2 only

1 and 3 only

2 and3 only

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 16:

The voltage and current characteristic of an element is as shown in the figure. The nature and value of the element are

A	Capacitor of 3.3 $μ F$	B	Inductor of 2.5 H
C	Capacitor of $6.7 μ F$	D	Inductor of 5.0 h

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 17:

In the circuit shown, what value of R will result in I=4A?

A	9Ω	B	7Ω
C	5.5Ω	D	3.5Ω

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 18:

In the circuit, as shown, the currents

I_{1}, I_{2} a n d I_{3}

through three resistors are,respectively

2.08A,2.92A and -0.08A

3.08A,2.5A and-0.06A

2.08A,2.5A and -0.08A

3.08A,2.92A and -0.06A

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 19:

The v-i relationship for a circuit containing R and C and a battery of voltage E, all in series is 1.

\frac{1}{C} \int i d t + i R = E

\frac{1}{R C} i + \frac{d i}{d t} - 0

\frac{1}{C} i + R \int i d t = E

which of the above relationship are correct?

1 and 2 only

1 and 3 only

2 and 3 only

1,2 and 3

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 20:

The flux-density at a distance of 0.1 m from a long straight wire, carrying a current of 200 A is

A	$5 \times 10^{- 4} W b / m^{2}$	B	$4 \times 10^{- 4} W b / m^{2}$
C	$3 \times 10^{- 4} W b / m^{2}$	D	$2 \times 10^{- 4} W b / m^{2}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 21:

A network graph with its tree shown by firm lines is given in the figure. The fundamental cut-set for the tree-branch number 2 is

1,2,3,4and 5

1,2 and 5

2,6,7 and 8

2,3 and 4

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 22:

A bipolar transistor has

α = 0.98 I_{c o} = 10 μ A .

If the base current is

100 μ A,

then collector current would be

2.91 mA

3.49 mA

4.91 mA

5.49 mA

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 23:

The reduced incidence matrix for a network is given as

1 2 3 4 5 6 \begin{matrix} a \\ A = b \\ c \end{matrix} [\begin{matrix} 1 & - 1 & - 1 & - 1 & 0 & 0 \\ 0 & 1 & 0 & 0 & - 1 & 1 \\ 0 & 0 & - 1 & 0 & 1 & 0 \end{matrix}]

Which of the following sets constitute a tree?

2,3and 5

1,2 and 6

1,2 and 4

1,2 and 3

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 24:

A triangular wave voltage, as shown in the figure, is applied across the terminals of a 0.5 F pure capacitor at time t=0.The corresponding current wave is

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 25:

Consider the following statements

Which of the statements given above is/are correct? Consider the following statements for Norton's theorem:

Short the branch resistance through which current is to be calculated
Obtain the current through this short-circuited branch, using any of the network simplifications teach niques
Develop North's equivalent circuit by connecting a current source $I_{N}$ with the resistance $R_{N}$ in series with it

Which of the statements given above is/are correct?

1,2 and 3

1 and 3 only

1 and 2 only

2 and 3 only

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 26:

For the network shown in the figure the current flowing the 5Ω resistance will be

A	$\frac{37}{25} A$	B	$\frac{40}{28} A$
C	$\frac{39}{28} A$	D	$\frac{41}{28} A$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 27:

The circuit as shown in the figure is connected to a load

Z_{L}

across X-X.For a maximum power transfer to the load

Z_{L}

should be

A	$\frac{3 - j}{4} Ω$	B	$\frac{3 + j}{4} Ω$
C	$\frac{3 j}{4} Ω$	D	$\frac{- 3 - j}{4} Ω$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 28:

In the networks as shown, with

I_{S I} = 5 A, I_{S I} = 10 A, V_{A B} = 120 V, a n d w i t h I_{S I} = 10 A, I_{S I} = 5 A, V_{A B} = 15 V .

What is the value of k to describe

I_{S I} = K I_{S 2}, s u c h t h a t V_{A B} = 0 ?

2.5

3.5

5.5

6.5

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 29:

For the circuit as shown, what is the value of C that leads to maximum power transfer to the load, If the value of L is 0.5H?

A	0.1 $μ F$	B	0.01 F
C	0.001F	D	$0.01 μ F$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 30:

The current in the 1Ω resistor in the network as shown is

2.00A

2.25A

2.50A

2.75A

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 31:

Which of the following is considered a time-domain technique in control systems?

Nyquist criterion

Bode plot

Root locus plot

Routh-Hurwitz criterion

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 32:

For the circuit, as shown, consider that switch

S_{1}

has been in position B for a very long and the switch

S_{2}

ahs been open all time. At time t=0, the switch

S_{1}

moves to position A and switch

S_{2}

close instantaneously. What is the value of

V_{o u t} a t t = 0^{+}

, assuming initial charge on C=0?

2.5 V

2.0V

1.5 V

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 33:

What is the phasor sum of currents

I_{1} = 10 (a - a^{2}) a n d I_{2} = - j 10

for two complex operators which are individually defined by

a^{3} = 1 a n d j^{2} = - 1

A	$17.32 ∠ 90 °$	B	$7.32 ∠ 90 °$
C	$17.32 ∠ 0 °$	D	$7.32 ∠ 0 °$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 34:

A series RLC circuit with R

= 2 Ω L = \frac{1}{2} H, C = \frac{1}{4} F

is excited by a 100V dc source. The circuit is initially in a quiescent state.The expression for the current response i (t) due to a dc source will be of the form

(k, k_{1}, k_{2})

is constants)

A	$K e^{- 4 t} \sin (4 t + \frac{π}{3})$	B	$K e^{- 2 t} \sin \sqrt{8} t$
C	$(K_{1} + k_{2} t) e^{- 2 t}$	D	$K_{1} e^{- 2 t} + K_{2} e^{- 4 t}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 35:

The impulse response of an LTI system is given by 5u(t). If the input to the system is given by

e^{- t}

then the output of the system is

A	$5 (1 - e^{- t}) u (t)$	B	$(1 - 5 e^{- t}) u (t)$
C	$5 - e^{- t} u (t)$	D	$5 u (t) - e^{- 1}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 36:

A pulse of + 10 V in magnitude and 2s in duration is applied to the terminals of a lossless inductor of 1.0H.The current through the inductor would

be a pulse of +20 A for the during of 2 s

be a pulse of -20 A for the during of 2 s

Increase linearly from zero to 20 A in 2 a, and in positive direction, and , from thereon, it remains constant at +20 A

Increase linearly from zero to -20 A in 2 a, and in positive direction, and , from thereon, it remains constant at -20 A

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 37:

A series RLC circuit has a resistance of 50Ω, inductance of 0.4H and a capacitor of 10

μ F .

The circuit is connected across a 100V supply. The resonance frequency and the current through the resistance are

500 rad/s and 2A

1000rad/s and 2A

500rad/s and 0.5A

1000rad/s and 0.5A

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 38:

Consider the following statements regarding power measurement of three-phase circuits by two wattmeter method

Total power can be measured if the three-phase load is balanced and can be represented by an equivalent Y connection only
Total power can be measured for the three-phase load irrespective of, whether the load is balanced or not connected in Y or $∆$
Power factor can be calculated only if the three-phase load is balanced

Which of the above statements are correct?

1 and 2 only

1 and 3 only

2 and 3 only

1,2 and 3

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 39:

In terms of ABCD-parameters of a 2-port network, the parameters

Z_{A}, Z_{B} a n d C_{C}

of the equivalent -T-network are, respectively

A	$\frac{A - 1}{C}, \frac{D - 1}{C} a n d \frac{1}{C}$	B	$\frac{A}{C}, \frac{D - 1}{C} a n d \frac{1}{C}$
C	$\frac{A - 1}{C}, \frac{D}{C} a n d \frac{1}{C}$	D	$\frac{A}{C}, \frac{D}{C} a n d B C$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 40:

The Z parameters

Z_{11}, Z_{12}, Z_{21} a n d Z_{22}

for the circuit as shown in the figure, respectively, are

A	$12 Ω, 4 Ω, 4 Ω a n d 6 Ω$	B	$8 Ω, 6 Ω, 4 Ω a n d 4 Ω$
C	$12 Ω, 6 Ω, 6 Ω a n d 4 Ω$	D	$8 Ω, 4 Ω, 6 Ω a n d 6 Ω$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 41:

A balanced 3-phase RYB sequence stays connected supply source with phase voltage 100V is connected to a delta connected balanced load 16-j12Ω per phase. The phase and line currents are, respectively

A	$5 \sqrt{3} A a n d 30 A$	B	$10 \sqrt{3} A a n d 30 A$
C	$5 \sqrt{3} A a n d 15 A$	D	$10 \sqrt{3} A a n d 15 A$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 42:

The maximum potential gradient that can be imposed in the air at atmospheric pressure without breakdown is 30kV/cm. The corresponding energy density is nearly

A	$30 J / m^{3}$	B	$35 J / m^{3}$
C	$40 J / m^{3}$	D	$45 J / m^{3}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 43:

A steady flow of 10 A maintained in a thin wire placed along the X-axis from (0,0,0) to (2,0,0) to find the value of the magnetic field intensity H at (0,0,5). when end effects are ignored, H is

A	$- 59.1 {\hat{a}}_{y} m / A / m$	B	$59.1 {\hat{a}}_{y} m / A / m$
C	$- 118.2 {\hat{a}}_{y} m / A / m$	D	$118.2 {\hat{a}}_{y} m / A / m$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 44:

A hollow metallic sphere of radius R is charged to a surface density of

σ

. The strength of the electric field inside the sphere a radius of r

(< R) i s

A	$\frac{σ}{{πr}^{2}}$	B	$\frac{σ}{2 {πr}^{2}}$
C	$\frac{σ}{4 {πr}^{2}}$	D	Zero

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 45:

In the circuit, as shown in the figure, the switched I closed at t=0. The current through the capacitor will decrease exponentially with a time constant of magnitude

0.5 s

1 s

2 s

4 s

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 46:

A parallel-plate capacitor with air between the plates has a capacitance of 10pF. If the distance between the parallel plated is halved and the space between the plates is filled with a material of dielectric constant 5, the newly formed capacitor will have a capacitance of

10pF

50pF

100pF

150pF

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 47:

Which of the following statements are correct regarding uniform plan waves?

Uniform plane waves are transverse
The relation between E and H is $\frac{E}{H} = \sqrt{\frac{\in}{μ}}$
E x H gives the direction of the wave travel
For a uniform plane wave travelling in x-direction, $E_{x} = 0$

1,2 and 3 only

1,3 and 4 only

1,2 and 4 only

2,3 and 4 only

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 48:

An energy meter makes 100 revolutions of its disc per unit of energy. The number of revolutions made by the disc during one hour when connected across 210V source and drawing a current of 20A at 0.8 p.f.leading is

336

316

286

256

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 49:

Consider the following statements regarding Computer Architecture:

The advantage with the dedicated bus is a decrease in size and cost
In synchronous timing, the occurrence of events on the bus is determined by the clock
Data bus width decides the number of bits transferred at one time

Which of the above statements are correct?

1 and 2 only

1 and 3 only

2 and 3 only

1,2 and 3

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 50:

Consider the following statements :

Better memory utilization is possible with contiguous allocation using fixed-size pages
Associative memory is used for providing fast access to data stored in cached memory.
Direct mapping of cache memory is hard to implement

Which of the above statements are correct?

1 and 2 only

1 and 3 only

1,2 and 3

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 51:

The decimal value 0.5 in IEEE single precision floating-point representation has fraction bits of

000....000 and exponent value of 0

000....000 and exponent value of -1

100....000 and exponent value of 0

100....000 and exponent value of -1

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 52:

What does the following program print? void f

(i n t^{*} p, i n t^{*} q)

{p = q; p_{*} = 2;}

} int i =0,j=1; int main ( )

{f (& i, & j); p r i n t ('' % d % d | n'' . i . j); g e t c h a r (); r e t u r n 0;}

2 2

2 1

0 1

0 2

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 53:

Consider the following set of processes with data thereof as given here:

Process	Arrival time	CPU Burst time
$P_{1}$	0 ms	12 ms
$P_{2}$	2 ms	4 ms
$P_{3}$	3 ms	6 ms
$P_{4}$	8ms	5 ms

An operating system uses the shortest remaining time first scheduling algorithm for pre-emptive scheduling of processes. The average waiting time of the processes is

7.5 ms

6.5 ms

5.5 ms

4.5 ms

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 54:

The length of cable required for transmitting data at the rate of 500Mbps in an Ethernet LAN with frames of size 10,000 bits for signal speed 2,00,000 km/s is

2.5 km

2.0 km

1.5 km

1.0 km

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 55:

Consider the following statements:

System calls provide the interface between a process and the operating system
PERL implementations include direct system call access
System calls occur in different ways depends on the computer is used

Which of the above statements are correct?

1 and 2 only

1 and 3 only

2 and 3 only

1,2 and 3

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 56:

What is the effective access time, if the average page-fault service time is 25 ms, memory access time is 100ns and page fault rate is P?

100+24,999,900 x P ns

100+25,000,000 x P ns

100+ 25,000 x p ns

25,000,000 + 100 P ns

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 57:

Consider the function fun I have shown below: int fun 1 (int num) { int count =0; while (num) { count ++; num>>=1; } return (count); } The value returned by fun 1(435) is

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 58:

Consider the following statements in the relevant context:

The two types of currents that flow in semiconductor diodes and transistors are dirt and diffusion currents
The junction region is called the depletion region or space-charge region
When currents flow through the diode in forwarding bias, the depletion region current is mostly of 'diffusion' type

Which of the above statements are correct?

1,2 and 3

1 and 2 only

1 and 3 only

2 and 3 only

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 59:

The bandwidth of a control system can be increased by using

Phase-lead network

Phase-lag network

Both Phase-lead network and Phase-leg network

Cascaded amplifier in the system

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 60:

Applications of negative feedback to centra in the amplifier reduced its gain from 200 to 100.If the gain with the same feedback is to another such appliance, the gain to the amplifier without feedback must have been

400

450

500

600

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 61:

Consider the following statements for a networks graph, if

B_{f}

is its fundamental tie set matrix corresponding to twigs and links, respectively:

$B_{t}$ is a unit matrix
$B_{l}$ s a rectangular matrix
The rank of $B_{f}$ is (b-n-1)

Where b is the number of branches and n is the number of nodes. Which of the above statements are correct?

1 and 2 only

1 and 3 only

2 and 3 only

None of the above

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 62:

An ideal operational amplifier is connected as shown in the figure. what is the output voltage

V_{2}

A	$3 V_{1}$	B	$2 V_{1}$
C	$1 V_{1}$	D	$\frac{V_{1}}{3}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 63:

The moderating index of an AM signal is reduced from 0.8 to 0.5. The ratio of the total power in the new modulated signal to that of the original signal will nearly be

0.39

0.63

0.85

1.25

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 64:

The Truth table for the functions

f (A B C D) = \sum_{m} (01, 3, 4, 8, 9) i s

A	B	C	f
0	0	0	W
0	0	1	X
0	1	0	Y
0	1	1	0
1	0	0	Z
1	0	1	0
1	1	0	0
1	1	1	0

Where W, X,Y, Z are given by (d is the complement of D)

D, d, 1, 1

1, d, D, 1

1, 1, D, d

1, D, d, 1

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 65:

An 8-bit DAC uses a ladder network. The full-scale output of the converter in percentage and in volts is,respectively

0.25% and 30 mV

0.39% and 30 mV

0.25% and 39 mV

0.39% and 39mV

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 66:

Consider the following statements :

Flash type ADCs are considered the fastest
In successive approximation type ADCs, conversion time depends upon the magnitude of the analogue voltage
Counter slope ADCs are considered the slowest

Which of the above statements are correct?

2 and 3 only

2 and 4 only

1 and 4 only

1 and 3 only

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 67:

For the feedback control system shown, if the steady state error is 20% for the unit step input signal, then the value of K must be

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 68:

The closed-loop transfer function

\frac{C (s)}{R (s)}

of the system represented by the signal flow graph as shown in the figure is

A	$\frac{G_{1} G_{2} G_{3} G_{4}}{(1 + G_{1} + G_{2})}$	B	$\frac{G_{1} G_{2} G_{3} G_{4}}{(1 + G_{3} + G_{4})}$
C	$\frac{G_{1} G_{2} G_{3} G_{4}}{(1 + G_{1} + G_{2}) (1 + G_{3} + G_{4})}$	D	$\frac{G_{1} G_{2} G_{3} G_{4}}{(1 + G_{1} + G_{2}) (1 + G_{3} G_{4})}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 69:

For the block diagram as shown in the figure, the overall transfer function

\frac{C}{R}

A	$\frac{G_{1} G_{2} H_{1}}{(1 - G_{1} H_{1} - G_{2} H_{2})}$	B	$\frac{G_{1} G_{2}}{(1 - G_{1} H_{1} + G_{2} H_{2})}$
C	$\frac{G_{1} G_{2}}{(1 + G_{1} H_{1} + G_{2} H_{2})}$	D	$\frac{G_{1} G_{2}}{(1 + G_{1} H_{1} - G_{2} H_{2})}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 70:

The block diagram shows a unity feedback closed-loop system. The steady-state error in the response to a unit step input is

14%

28%

42%

57%

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 71:

The open-loop transfer function of negative feedback is

G (s) H (s) = \frac{K}{s (s + 5) (s + 12)}

For ensuring system stability the gain K should be in the range

K>1020

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 72:

The characteristic polynomial of a feedback control system is given by

R (s) = s^{5} + 2 s^{4} + 2 s^{3} + 4 s^{3} + 11 s + 10

For this system, the numbers of roots that lie in the left hand and right-hand s-plane respectively, are

5 and 0

4 and 1

3 and 2

2 and 3

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 73:

The open-loop transfer function G(s)H9s) of a Bode's plot for feedback system as shown in the figure is

A	$\frac{K (s + 5)}{s^{2} (s + 10)}$	B	$\frac{K (s + 5)}{(s + 10)}$
C	$\frac{K (s + 10)}{s^{2} (s + 5)}$	D	$\frac{K (s + 10)}{s (s + 5)}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 74:

A system with the characteristic equation

s^{4} + 2 s^{3} + 11 s^{2} + 18 s + 18 = 0,

will have closed-loop poles such that

All poles lie in left half of the s-plane and no pole lies on imaginary axis

All poles lie in the right half of the s-plane

Two poles lie symmetrically on the imaginary axis of the s-plane

All four poles lie on the imaginary axis of the s-plane

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 75:

The open-loop transfer function G(s)H(s) of a root locus plot of a system as shown in the figure is

A	$\frac{4}{{(S + 1)}^{1}}$	B	$\frac{4}{{(S + 1)}^{2}}$
C	$\frac{4}{{(S + 1)}^{3}}$	D	$\frac{4}{{(S + 1)}^{4}}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 76:

The transfer function of a compensator is

\frac{(1 + 3 s T)}{(1 + s T)} .

The maximum possible phase shift is.

A	$30 °$	B	$45 °$
C	$60 °$	D	$90 °$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 77:

The steady-state response c(t) for an input r(t) =sin 2t to a system transfer function

\frac{1}{s + 4} i s

A	0.25 Sin2t	B	$\sin (2 t - 45 °)$
C	$0.316 \sin (2 t - 26.5 °)$	D	$0.632 \cos 2 t$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 78:

Compensation derived from the P-D network whose differential equation is governed by

e_{o} = 20 (e_{1} + T \frac{d e_{i}}{d t})

as shown in the figure is to be investigated. For what value of T will the closed-loop response be critically damped?

1.612

0.806

0.306

0.161

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 79:

The unity feedback system as shown in the figure is characterized by

G (s) = \frac{1}{{(s + 1)}^{2}} .

The output time response will have a damping factor ζ, and natural frequency

ω_{n},

respectively, as

A	0.707 and 1	B	$0.866 a n d \sqrt{2}$
C	$0.707 a n d \sqrt{2}$	D	0.866 and 1

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 80:

For a state model

\dot{X = A X, w h e r e A = [\frac{1}{1} \frac{0}{1}]}, t h e s t a t e

transition matrix is

A	$[\frac{t e^{- t}}{e^{t}} \frac{0}{e^{t}}]$	B	$[\frac{0}{e^{t}} \frac{t}{t e^{t}}]$
C	$[\frac{e^{- t}}{t e^{t}} \frac{0}{e^{t}}]$	D	$[\frac{t}{t^{2}} \frac{0}{e^{t}}]$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 81:

A unit step input to a unity feedback system is shown in the figure, the time for peak overshoot is,nearly

0.35 s

0.58 s

0.79 s

0.96 s

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 82:

The transient response of second-order underdamped system starting from rest is given by

c (t) = A e^{- 6 t} \sin (8 t + θ), t \geq 0 .

The natural frequency of the system is

100

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 83:

For a feedback control system, all the roots of characters equations can be placed at the desired location in the s-plane of only the system is

Observable
Controllable

Which of the above statements are correct?

1 only

2 only

Both 1 and 2

Neither 1 nor 2

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 84:

A second-order system with a zero at -2 has its poles located at -3+j4 and -3-j4 in the s-plane . The undamped natural frequency and the damping factor of the system respectively are

3 rad/s and 0.80

5 rad/s and 0.80

3 rad/s and 0.60

5 rad/s and 0.60

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 85:

What is the error rate factor

K_{e}

to yield a damping factor of 0.5 for the system shown in the block diagram?

0.116

0.232

0.284

0.332

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 86:

An ideal transformer is having 150 turns primary and 750 turns secondary. The primary coil is connected to a 240 V,%50Hz source, The secondary winding supplies a load of 4A at a lagging power factor of 0.8.what is the power supplied by the transformer to the load?

4200 W

3840 W

2100 W

1920 W

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 87:

In an induction motor for a fixed speed at constant frequency

Both line current and torque are proportional to voltage

Both line current and torque are proportional to the square of voltage

Line current is proportional to voltage and torque is proportional o the square of voltage

Line current is constant and torque is proportional to voltage

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 88:

In a core-type single-phase transformer the steel core is assembled by staggering butt-joints in adjacent layers of laminations vide figures. The purpose served is said to be

Avoiding continuous air-gap
Preventing loss of mechanical strength
Reducing eddy-current loss

Which above the statements are correct?

1 and 2 only

1 and 3 only

2 and 3 only

1,2 and 3

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 89:

Which of the following would refer to an ideal transformer?

Winding resistance is negligible
Leakage-fluxes are included
Core-losses are negligible
Magnetization characteristic is a liner

1,2 and 3 only

1,3 and 4 only

1,2 and 4 only

2,3 and 4 only

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 90:

A 24-slot, 2-pole,lap-wound dc machine has 18 turns per coil. The average flux density per pole is 1 Tesla. The effective length of the machine is 20 cm and the radius of the armature is 10cm. The magnetic poles cover 80% of the armature periphery. For armature angular velocity

(ω_{m})

of 183.2 rad/sec, the induced emf in the armature winding is nearly

585V

1050V

1260V

1465V

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 91:

A 220V dc compound generator connected in long-shunt made has the following parameters:

R_{a} = 0.1 Ω, R_{s h} = 80 Ω, R_{s e r i e s} = 0.05 Ω .

For a load of

150 ∆

at rated terminal voltage, the include emf of the generator should nearly be

233V

243V

251V

262V

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 92:

The Laplace transform of

f (t) = t^{n} e^{- α t} u (t) i s

A	$\frac{(n + 1)!}{{(s + α)}^{n + 1}}$	C	$\frac{n!}{{(s + α)}^{n}}$
B	$\frac{(n - 1)!}{{(s + α)}^{n + 1}}$	D	$\frac{n!}{{(s + α)}^{n + 1}}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 93:

A dc shunt motor has the following characteristics,

R_{a} = 0.5 Ω, R_{f} = 200 Ω,

based speed=1000rpm, rated voltage=250V.On no load, it draws a current=5A. At what speed will this run while delivering a torque of 150N.m?

881rpm

920rpm

950rpm

990rpm

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 94:

The figure shows plots of speed (N) Vs.armature current

(I_{a})

of a motor for two different operating conditions. Which one of the following feature is relevant?

(1) represents stronger shunt field,and (2) represents stronger series field of a compound motor

(1) represents stronger series field and (2) represents stronger shunt field of compound motor

(1) represents only shunt excitation, and (2) represents only series excitation)

(1) represents only series excitation and (2) represents only shunt excitation

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 95:

A 230V,50Hz,4-pole,single-phase induction motor is rotating clockwise (forward) direction at a speed of 1425rpm. If the rotor resistance at standstill is 7.8

Ω

, then the effective rotor resistance in the backward branch of the equivalent circuit will be

A	$2.0 Ω$	B	$4.0 Ω$
C	$7.8 Ω$	D	$156 Ω$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 96:

A 400V, 50Hz,30hp, three-phase induction motor is drawing 50 A current at 0.8 power factor lagging. The stator and rotor copper losses are 1.5KW and 900W respectively. The friction and windage losses are 1050 W and the core losses are 1200W.The air gap power of the motor will be, nearly

15kW

20kW

25kW

30kW

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 97:

When the value of slip of an induction motor approaches zero, the effective resistance

is very low and the motor is under no-load

of the rotor circuit is very high and the motor is under no-load

is zero

of the rotor circuit is infinity and the motor is equivalent to short circuited two winding transformer

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 98:

A4-pole,%50Hz,3-phase induction motor with a rotor resistance of

0.25 Ω

develops a maximum torque of 25N.m at 1400rpm.The rotor reactance

x_{2}

and slip at maximum torque

m_{s} a x, T

respectively would be

A	$2.0 a n d \frac{1}{15}$	B	$3.75 a n d \frac{1}{12}$
C	$2.0 a n d \frac{1}{12}$	D	$3.75 a n d \frac{1}{15}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 99:

A-3-phase,37kW induction motor has an efficiency of 90% when delivering a full load. At this load, the stator copper losses and rotor copper are equal and are equal to stator iron losses. The mechanical losses are one-third of no-load losses.Then the motor runs at a slip of

0.01

0.02

0.03

0.04

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 100:

The rotor of a 4-pole ac generator is wound with a 200 turns coil. If the flux per pole is 5m Wb and the rotor runs at a speed of 1500rpm, the rpm value of the induced voltage for this ca generator is nearly

140V

157V

164V

200V

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 101:

A 3-MVA,6-pole,50Hz,3-phase synchronous generator is connected to an infinite bus of 3300V; and it is run at 1000rpm. The synchronous reactance of the machine is 0.915

Ω

per phase. The synchronizing torque for

1 °

mechanical displacement of the rotor is

7500N.m

7000N.m

6000N.m

4500N.m

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 102:

The second-harmonic component of the power P versus load angle δ characteristic of a synchronous machine, operating at a terminal voltage

V_{t}

and having the d-and q-axis reactance per phase of

X_{d}

and

X_{q}

,respectively ,is

A	$\frac{V_{t}^{2}}{2} . \frac{X_{d} X_{q}}{X_{d} + X_{q}} \sin 2$ δ	B	$\frac{V_{t}^{2}}{2} (\frac{1}{X_{q}} - \frac{1}{X_{d}}) \sin 2$ δ
C	$\frac{V_{t}^{2}}{2} . \frac{X_{d} X_{q}}{X_{d} + X_{q}} \cos 2$ δ	D	$\frac{V_{t}^{2}}{2} (\frac{1}{X_{q}} - \frac{1}{X_{d}}) \cos 2$ δ

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 103:

The term Synchronous condenser refers to

A synchronous motor with a capacitor connected across the stator terminals to improve the power factor

A synchronous motor operating at full-load with leading power factor

An over-excited synchro motor partially supplying mechancical load and also improving the power factor of the system to which it is connected

An over-excited synchronous motor operating at no-load with leading power factor used in large power stations for improvement of power factor

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 104:

Which of the following operating aspects necessitating the computation of Regulation of an alternator?

When the load is thrown off
For designing an automatic voltage-control equipment
For determination of steady-state and transient stability
For parallel operation of alternators

1,2 and 3 only

1,2 and 4 only

1,3 and 4 only

1,2,3 and 4

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 105:

A 2 phase ac servomotor has a tendency to run as a single-phase induction motor if the voltage across the control winding becomes zero. To prevent this

Rotor having high mass and moment of inertia is to be used

Drag-cup type of light rotor and high resistance is to be used

A low resistance rotor is to be used

The number of turns in the control winding is to be kept lesser than in the main reference winding

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 106:

A single-stack,8-phase(stator),multiple-step motor has 6rotor teeth.The poles are excited one at a time. If the excitation frequency is 120 Hz,the speed of the motor is

3 rps

5 rps

10 rps

15 rps

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 107:

An extra-high voltage transmission line of length 3001cm can be approximated by a lossless line having propagation cottage

β

=0.00127 rad/km. The percentage ratio of line length to wavelength will nearly be

24%

19%

12%

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 108:

A lossy capacitor

C_{x},

rated for the operation of 5kV,50Hz is represented by an equivalent circuit with an ideal capacitor

C_{p}

in parallel with a resistor

R_{p} . C_{p}

is 0.102

μ F;

and

R_{p} = 1.25 M Ω .

The power loss, and tanδ, of the lossy capacitor, when operating at the rated voltage are respectively

20 W W and 0.04

10 W and 0.04

20 W and 0.025

10 W and 0.025

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 109:

The time interval needed for a surge to travel to the end of a 600 km long overhead transmission line is

6 s

2 s

20 ms

2 ms

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 110:

At what power factor will a lossless line with a reactance of 0.6 exhibits zero regulation given that the sending end voltage is 1.0 up?

0.800 lag

0.800 lead

0.954 lead

Unity p.f.

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 111:

An 11 kV,3-phase transmission line has a resistance of 1.5 Ω and reactance of 4 Ω per phase. The efficiency of the line when supplying the load of 4 MW at 0.8 lagging power factor is nearly

99%

95%

92%

90%

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 112:

The dielectric loss in the insulation of a lossy underground cable, due to leakage current is (using standard notations)

A	$ω C V^{2} C o s$ δ	B	$ω C V \tan$ δ
C	$ω C V^{2} \tan$ δ	D	$ω C V \sin$ δ

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 113:

A 3-phase, 100 MVA,11 kV generator has the following p.u constants. The generator natural is solidly grounded.

X_{1} = X_{2} = 3 X_{0} = 0.15 Ω

. The ratio of the fault current due to three-phase dead-short-circuit to that due to L-G fault would be nearly

0.33

0.56

0.78

1.0

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 114:

A balanced 3-phase load is supplied from a 3- phase supply. The contact inline c of the triple-pole switch contactor fails to connect when switched on. If the line-currents in lines a and b record 25A each, then the positive-sequence component of the current is

A	$14.4 ∠ + 30 ° A$	B	$25.0 ∠ + 30 ° A$
C	$14.4 ∠ - 30 ° A$	D	$25.0 ∠ + 30 ° A$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 115:

In a circuit-breaker, the are is produced due to

Thermal emission
The high temperature of the air
Field emission

Which of the above statements are correct?

1,2 and 3

2 and 3 only

1 and 2 only

1and 3 only

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 116:

The line reactance of a power network is as follows:

Line No.	From Bus	To Bus	Reactance
1	0	1	0.2 p.u
2	1	2	0.4 p.u

The bus impendence matrix with '0' as ref-bus is

A	$[\frac{0.2}{0.4} \frac{0.4}{0.6}]$	B	$[\frac{0.4}{0.2} \frac{0.2}{0.6}]$
C	$[\frac{0.2}{0.2} \frac{0.2}{0.6}]$	D	$[\frac{0.6}{0.2} \frac{0.2}{0.4}]$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 117:

An alternator is

A polyhase synchronous machine operated with DC exciter

A polyphase synchronous machine operated with AC exciter

A thee-phase induction machine with prime mover

Any AC generator

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 118:

The stability of a system, when subjected to a disturbance, is assessable by which of the following methods?

Swing curve
Equal-area criterion
Power-angle diagram
Power-circle diagram

1,2 and 4 only

1,3 and 4 only

2,3 and 4 only

1,2 and 3 only

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 119:

Power transmission capacity of a high voltage line can be increased by

Increasing the resistance of the line

Incerasing the inductive reactance of the line

Reducing the effective series reactance of the line

Reducing the shunt admittance of the line

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 120:

A 40MVA,11kV,3-phase,50Hz,4-pole turbo-alternator has an inertia constant of 15sec.An input of 20MW developed 15MW of output power (Neglecting losses). Then the accelerations are

A	$60 ° / s^{2}$	B	$65 ° / s^{2}$
C	$70 ° / s^{2}$	D	$75 ° / s^{2}$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 121:

In a Progressive Simplex Lap Winding for a 4-pole,14-slot,2 coil-siders per slot d.c armature, the back pitch

y_{b}

and front pitch

y_{f}

will be respectively

7 and 5

5 and 5

7 and 7

5 and 7

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 122:

The starting current in an induction motor is 5 times the full-load current while the full load slip is 4% The ratio of starting torque to full-load torque is

0.6

0.8

1.0

1.2

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 123:

When a bundle of conductors are used in place of single conductors the effective inductance and capacitance will,respectively

Increase and decreases

Decreases and increase

Decreases and remain unaffected

Increased and remain unaffected

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 124:

A buck regulator has an input voltage of 12V and the required output voltage is 5V.what is the duty cycle of the regulator?

A	$\frac{5}{12}$	B	$\frac{12}{5}$
C	$\frac{5}{2}$	D	$6$

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 125:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): An electrolytic capacitor consists of two electrodes immersed in an electrolyte with a chemical film on one of the electrodes acting as the dielectric Statements (II): The electrolytic capacitor may be operated with any of the electrodes as anode positive with respect to the other

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 126:

I_{1} a n d I_{2}

cannot be connected in series. Statements (II): Superposition Theorem cannot be applied to current sources when one terminal of each of these sources is connected to a common node.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 127:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Both Coupling capacitance and Emitter bypass capacitance affect the low-frequency response of an R-C-coupled amplifier Statements (I): Both stray capacitances and Emitter-to-base diffusion capacitance have a profound effect response of an R-C-couple amplifier.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 128:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A ' bedding' is provided over to the metallic sheath in an underground cable Statements (I): The bedding protects the metallic against corrosion

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 129:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Zero-sequence currents are, by definition in phase with each other in the three windings of any three windings of any three-phase apparatus Statements (I): They may be caused by magnetic saturation in the transformers.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 130:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): 'High resistance' method is used for our extinction in DC circuit breakers. Statements (I): Very little energy is dissipated in the arc in the high resistance method of arc extinction.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 131:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A radial main system, circuit experience low voltage at the far end under heavy load conditions Statements (I): The voltage at the far end under heavy loading can be corrected by connecting a shunt capacitor compensator there.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 132:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): In an HVDC system, the steady-state power transfer from a generator to the infinite bus is dependent on the power angle and the line impedance intervening between them. Statements (I): In an HVDC system, the power transfer between the two stations connected by a dc link is much than that in a corresponding EHV ac system.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 133:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Conventional diode rectifier circuit have low-frequency harmonics. Statements (I): Passive techniques used to reduce the current THD in conventional rectifiers require large transformers and/or reactors.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 134:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Resonant inverters are used as electronic ballasts for gas discharge lamps, induction heating etc. Statements (I): A DC to high-frequency AC resonant inverter may be obtained by applying the square wave voltage obtained from a DC source and switch network operating frequency

f_{s}

to a tuned tank circuit designed for frequency

f o

, so as to obtain variable magnitudes of v(t) and i(t) by matching

f_{s} a n d f_{0} .

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 135:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): In liner commutation, the magnitude of the current in the coils under each pole in a DC generator and a given load remains constant. Statements (I): The magnitude of the emf induced in the coils under each pole of a DC generator on load remains constant .

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 136:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A very efficient method of speed control of an induction motor is to vary both V and f in such a way that

\frac{V}{f}

the ratio remains constant. Statements (I): Keeping

\frac{V}{f}

constant allows the magnetic flux to remain constant and a reduced V reduces the inrush of starting current.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 137:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Windings of most power transformers are immersed in a tank of oil. Statements (I): Convection currents in the insulting oil help carry the heat away from the windings and the core.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 138:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A large gate pulse is required to turn on a GTO thyristor. Statements (I): This thyristor does not need a commutation circuit.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 139:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): The decimal to-BCD encoder digital logic circuit chip IC 74147, is a priority encoder. Statements (II): In this circuit, priority is given to the lowest-order input.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 140:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Analog to digital conversion is essentially a sampling process. Statements (I): Ahold elements are digital to analogue converter.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 141:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): High-level programming languages preferred by the scientific community as they are user friendly Statements (I): High -level programming languages provide ways of detailing instruction for problem-solving that are translated into the low-level language via compilers and interpreters before being executed by the computer.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 142:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): The conductivity of an intrinsic semiconductor increases exponentially with temperature. Statements (I): As the temperature rises, more and more covalent bonds are broken resulting in more electron-hole pairs.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 143:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Light is capable of transferring electrons to the free-state inside a material, thus increasing the electrical conductivity of the material. Statements (I): The increased electrical conductivity produced by light is called photo-conductivity.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 144:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A general-purpose dynamometer type wattmeter does not accurately at low power factors. Statements (I): The presence of self-inductance of the pressure coil introduces an error.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 145:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A dynamometer type wattmeter has a linear scale while a dynamometer type voltmeter has a non-liner scale. Statements (II): Deflecting torque developed in a dynamometer type wattmeter is proportional o the power and that developed in a dynamometer type ammeter is proportional to the square of the current.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 146:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): The rating disc in an energy meter is made of a magnetic material. Statements (II): Braking takes place due to the eddy current generated by the braking magnet.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 147:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): When a solid surface is bombarded by electrons of appreciable energy, secondary emission occurs from the surface. Statements (I): The major application of the secondary emission is in voltage amplification.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 148:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Electromagnetic flowmeter is preferred for flow velocity measurement of slurries in pipes as long as the slurry has adequate electrical conductivity. Statements (II): Electromagnetic flow meter does not insert any instrument parts into the fluid flow to cause an obstruction as in most other flowmeters.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 149:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Direct access method is based on a disk model of a file. Statements (II): Disks allow random access to any file block.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

Category: UPSC | Engineering Services (Preliminary) Examination | 2018 | Electrical Engineering

Question 150:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Variables that are defined inside subprograms are local variables. Statements (II): Their scope is in the body of the subprogram in which they are defined.

Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Statements (I) is true; but statements (II) is false

Statements (I) is false ; but statements (II) is true

⮜ Back Next ⮞

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Answered & Marked for Review (will be considered for evaluation)

Question 1:

Eigenvalues of the Matrix

[\begin{matrix} 3 & - 1 & - 1 \\ - 1 & 3 & - 1 \\ - 1 & - 1 & 3 \end{matrix}] a r e

Correct Answer : 1,4,4

Question 2:

The solution of the differential equation

\frac{d^{2} y}{d x^{2}} - \frac{d y}{d x} - 2 y = 3 e^{2 x},

where,y(0)=0 and y'(0)=-2 is

A	$y = e^{- x} - e^{2 x} + x e^{2 x}$	B	$y = e^{x} - e^{- 2 x} - x e^{2 x}$
C	$y = e^{- x} + e^{2 x} + x e^{2 x}$	D	$y = e^{x} - e^{- 2 x} + x e^{2 x}$

Correct Answer : A

Question 3:

If Z=

e^{a x + b y}

F(ax-by); the value of

b . \frac{\partial Z}{\partial x} + a \frac{\partial Z}{\partial y} i s

Correct Answer : 2abZ

Question 4:

The general integral of the partial differential equation

y^{2} p - x y q = x (z - 2 y) i s

A	$ϕ (x^{2} + y^{2}, y^{2} - y z) = 0$	B	$ϕ (x^{2} - y^{2}, y^{2} + y z) = 0$
C	$ϕ (x y, y z) = 0$	D	$ϕ (x + y, I n x - z) = 0$

Correct Answer : A

Question 5:

\frac{d^{2} y}{d t^{2}} + y = 0

under the conditions

y = 1, \frac{d y}{d t} = 0, w h e n t = 0,

then y is equal to

Correct Answer : cos t

Question 6:

If the system 2x-y+3z=2 x+y+2z=2 5x-y+az=b has infinitely many solutions, then the values of and b, respectively,are

Correct Answer : 8 and 6

Question 7:

Evaluate

\oint \frac{1}{c {(z - 1)}^{3} . (z - 3)} d z

where c is the rectangular region defined by x=0,x=4,y=-1and y=1

A	1	B	0
C	$\frac{π}{2} i$	D	$π (3 + 2 i)$

Correct Answer : B

Question 8:

The Fourier Transform of e

- \frac{x^{2}}{2} i s

A	$\frac{1}{2} . e^{- \frac{w^{2}}{2}}$	B	$e^{- \frac{w^{2}}{2}}$
C	$\frac{π}{2}$	D	$\sqrt{π}$

Correct Answer : B

Question 9:

Correct Answer : 12

Question 10:

Consider a random variable to which a Poisson distribution is best fitted. It happens that

P_{(X = 1)} = \frac{2}{3} P_{(x = 2)}

on this distribution plot. The variance of this distribution will be

A	3	B	3
C	1	D	$\frac{2}{3}$

Correct Answer : A

Question 11:

In Face-centered Cubic structure (FCC), what a number of atoms is present in each unit cell?

Correct Answer : 14

Question 12:

A	${(\frac{M p}{n N})}^{\frac{1}{3}}$	B	${(\frac{N M}{n p})}^{\frac{1}{3}}$
C	${(\frac{n M}{N p})}^{\frac{1}{3}}$	D	${(\frac{N p}{n M})}^{\frac{1}{3}}$

Correct Answer : C

Question 13:

The magnetic susceptibility of aluminium is

2.1 \times 10^{- 5}

. The permeability and relative permeability are, respectively

A	$12.6 \times 10^{- 7} a n d 1.0021$	B	$1.26 \times 10^{- 7} a n d 1.0021$
C	$12.6 \times 10^{- 7} a n d 1.000021$	D	$1.26 \times 10^{- 7} a n d 1.000021$

Correct Answer : C

Question 14:

An iron rod of

10^{- 3} m^{3}

volume and relative permeability of 1150 is placed inside a solenoid wound with 5turns/cm. If a current of 0.5 A is allowed to pass through the solenoid, the magnetic of the rod is

A	$2.87 \times 10^{4} A . m^{2}$	B	$28.7 \times 10^{3} A . m^{2}$
C	$2.87 \times 10^{2} A . m^{2}$	D	$28.7 \times 10^{2} A . m^{2}$

Correct Answer : C

Question 15:

When an alternating voltage of a given frequency is applied to a dielectric material, dissipation of energy occurs due to

Continual change in the orbital paths of the electrons in the atomic structure
A small conduction current through the dielectric
Eddy currents

Which of the above statements are correct?

Correct Answer : 1 and 2 only

Question 16:

The voltage and current characteristic of an element is as shown in the figure. The nature and value of the element are

A	Capacitor of 3.3 $μ F$	B	Inductor of 2.5 H
C	Capacitor of $6.7 μ F$	D	Inductor of 5.0 h

Correct Answer : B

Question 17:

In the circuit shown, what value of R will result in I=4A?

A	9Ω	B	7Ω
C	5.5Ω	D	3.5Ω

Correct Answer : B

Question 18:

In the circuit, as shown, the currents

I_{1}, I_{2} a n d I_{3}

through three resistors are,respectively

Correct Answer : 2.08A,2.92A and -0.08A

Question 19:

The v-i relationship for a circuit containing R and C and a battery of voltage E, all in series is 1.

\frac{1}{C} \int i d t + i R = E

\frac{1}{R C} i + \frac{d i}{d t} - 0

\frac{1}{C} i + R \int i d t = E

which of the above relationship are correct?

Correct Answer : 1 and 2 only

Question 20:

The flux-density at a distance of 0.1 m from a long straight wire, carrying a current of 200 A is

A	$5 \times 10^{- 4} W b / m^{2}$	B	$4 \times 10^{- 4} W b / m^{2}$
C	$3 \times 10^{- 4} W b / m^{2}$	D	$2 \times 10^{- 4} W b / m^{2}$

Correct Answer : B

Question 21:

A network graph with its tree shown by firm lines is given in the figure. The fundamental cut-set for the tree-branch number 2 is

Correct Answer : 2,6,7 and 8

Question 22:

A bipolar transistor has

α = 0.98 I_{c o} = 10 μ A .

If the base current is

100 μ A,

then collector current would be

Correct Answer : 4.91 mA

Question 23:

The reduced incidence matrix for a network is given as

1 2 3 4 5 6 \begin{matrix} a \\ A = b \\ c \end{matrix} [\begin{matrix} 1 & - 1 & - 1 & - 1 & 0 & 0 \\ 0 & 1 & 0 & 0 & - 1 & 1 \\ 0 & 0 & - 1 & 0 & 1 & 0 \end{matrix}]

Which of the following sets constitute a tree?

Correct Answer : 1,2 and 3

Question 24:

A triangular wave voltage, as shown in the figure, is applied across the terminals of a 0.5 F pure capacitor at time t=0.The corresponding current wave is

Correct Answer : B

Question 25:

Consider the following statements

Which of the statements given above is/are correct? Consider the following statements for Norton's theorem:

Short the branch resistance through which current is to be calculated
Obtain the current through this short-circuited branch, using any of the network simplifications teach niques
Develop North's equivalent circuit by connecting a current source $I_{N}$ with the resistance $R_{N}$ in series with it

Which of the statements given above is/are correct?

Correct Answer : 1 and 2 only

Question 26:

For the network shown in the figure the current flowing the 5Ω resistance will be

A	$\frac{37}{25} A$	B	$\frac{40}{28} A$
C	$\frac{39}{28} A$	D	$\frac{41}{28} A$

Correct Answer : C

Question 27:

The circuit as shown in the figure is connected to a load

Z_{L}

across X-X.For a maximum power transfer to the load

Z_{L}

should be

A	$\frac{3 - j}{4} Ω$	B	$\frac{3 + j}{4} Ω$
C	$\frac{3 j}{4} Ω$	D	$\frac{- 3 - j}{4} Ω$

Correct Answer : A

Question 28:

In the networks as shown, with

I_{S I} = 5 A, I_{S I} = 10 A, V_{A B} = 120 V, a n d w i t h I_{S I} = 10 A, I_{S I} = 5 A, V_{A B} = 15 V .

What is the value of k to describe

I_{S I} = K I_{S 2}, s u c h t h a t V_{A B} = 0 ?

Correct Answer : 2.5

Question 29:

For the circuit as shown, what is the value of C that leads to maximum power transfer to the load, If the value of L is 0.5H?

A	0.1 $μ F$	B	0.01 F
C	0.001F	D	$0.01 μ F$

Correct Answer : B

Question 30:

The current in the 1Ω resistor in the network as shown is

Correct Answer : 2.75A

Question 31:

Which of the following is considered a time-domain technique in control systems?

Correct Answer : Bode plot

Question 32:

For the circuit, as shown, consider that switch

S_{1}

has been in position B for a very long and the switch

S_{2}

ahs been open all time. At time t=0, the switch

S_{1}

moves to position A and switch

S_{2}

close instantaneously. What is the value of

V_{o u t} a t t = 0^{+}

, assuming initial charge on C=0?

Correct Answer : 0V

Question 33:

What is the phasor sum of currents

I_{1} = 10 (a - a^{2}) a n d I_{2} = - j 10

for two complex operators which are individually defined by

a^{3} = 1 a n d j^{2} = - 1

A	$17.32 ∠ 90 °$	B	$7.32 ∠ 90 °$
C	$17.32 ∠ 0 °$	D	$7.32 ∠ 0 °$

Correct Answer : A

Question 34:

A series RLC circuit with R

= 2 Ω L = \frac{1}{2} H, C = \frac{1}{4} F

is excited by a 100V dc source. The circuit is initially in a quiescent state.The expression for the current response i (t) due to a dc source will be of the form

(k, k_{1}, k_{2})

is constants)

A	$K e^{- 4 t} \sin (4 t + \frac{π}{3})$	B	$K e^{- 2 t} \sin \sqrt{8} t$
C	$(K_{1} + k_{2} t) e^{- 2 t}$	D	$K_{1} e^{- 2 t} + K_{2} e^{- 4 t}$

Correct Answer : B

Question 35:

The impulse response of an LTI system is given by 5u(t). If the input to the system is given by

e^{- t}

then the output of the system is

A	$5 (1 - e^{- t}) u (t)$	B	$(1 - 5 e^{- t}) u (t)$
C	$5 - e^{- t} u (t)$	D	$5 u (t) - e^{- 1}$

Correct Answer : B

Question 36:

A pulse of + 10 V in magnitude and 2s in duration is applied to the terminals of a lossless inductor of 1.0H.The current through the inductor would

Correct Answer : Increase linearly from zero to 20 A in 2 a, and in positive direction, and , from thereon, it remains constant at +20 A

Question 37:

A series RLC circuit has a resistance of 50Ω, inductance of 0.4H and a capacitor of 10

μ F .

The circuit is connected across a 100V supply. The resonance frequency and the current through the resistance are

Correct Answer : 500 rad/s and 2A

Question 38:

Consider the following statements regarding power measurement of three-phase circuits by two wattmeter method

Total power can be measured if the three-phase load is balanced and can be represented by an equivalent Y connection only
Total power can be measured for the three-phase load irrespective of, whether the load is balanced or not connected in Y or $∆$
Power factor can be calculated only if the three-phase load is balanced

Which of the above statements are correct?

Correct Answer : 2 and 3 only

Question 39:

In terms of ABCD-parameters of a 2-port network, the parameters

Z_{A}, Z_{B} a n d C_{C}

of the equivalent -T-network are, respectively

A	$\frac{A - 1}{C}, \frac{D - 1}{C} a n d \frac{1}{C}$	B	$\frac{A}{C}, \frac{D - 1}{C} a n d \frac{1}{C}$
C	$\frac{A - 1}{C}, \frac{D}{C} a n d \frac{1}{C}$	D	$\frac{A}{C}, \frac{D}{C} a n d B C$

Correct Answer : A

Question 40:

The Z parameters

Z_{11}, Z_{12}, Z_{21} a n d Z_{22}

for the circuit as shown in the figure, respectively, are

A	$12 Ω, 4 Ω, 4 Ω a n d 6 Ω$	B	$8 Ω, 6 Ω, 4 Ω a n d 4 Ω$
C	$12 Ω, 6 Ω, 6 Ω a n d 4 Ω$	D	$8 Ω, 4 Ω, 6 Ω a n d 6 Ω$

Correct Answer : A

Question 41:

A balanced 3-phase RYB sequence stays connected supply source with phase voltage 100V is connected to a delta connected balanced load 16-j12Ω per phase. The phase and line currents are, respectively

A	$5 \sqrt{3} A a n d 30 A$	B	$10 \sqrt{3} A a n d 30 A$
C	$5 \sqrt{3} A a n d 15 A$	D	$10 \sqrt{3} A a n d 15 A$

Correct Answer : C

Question 42:

The maximum potential gradient that can be imposed in the air at atmospheric pressure without breakdown is 30kV/cm. The corresponding energy density is nearly

A	$30 J / m^{3}$	B	$35 J / m^{3}$
C	$40 J / m^{3}$	D	$45 J / m^{3}$

Correct Answer : C

Question 43:

A steady flow of 10 A maintained in a thin wire placed along the X-axis from (0,0,0) to (2,0,0) to find the value of the magnetic field intensity H at (0,0,5). when end effects are ignored, H is

A	$- 59.1 {\hat{a}}_{y} m / A / m$	B	$59.1 {\hat{a}}_{y} m / A / m$
C	$- 118.2 {\hat{a}}_{y} m / A / m$	D	$118.2 {\hat{a}}_{y} m / A / m$

Correct Answer : A

Question 44:

A hollow metallic sphere of radius R is charged to a surface density of

σ

. The strength of the electric field inside the sphere a radius of r

(< R) i s

A	$\frac{σ}{{πr}^{2}}$	B	$\frac{σ}{2 {πr}^{2}}$
C	$\frac{σ}{4 {πr}^{2}}$	D	Zero

Correct Answer : D

Question 45:

In the circuit, as shown in the figure, the switched I closed at t=0. The current through the capacitor will decrease exponentially with a time constant of magnitude

Correct Answer : 1 s

Question 46:

Correct Answer : 100pF

Question 47:

Which of the following statements are correct regarding uniform plan waves?

Uniform plane waves are transverse
The relation between E and H is $\frac{E}{H} = \sqrt{\frac{\in}{μ}}$
E x H gives the direction of the wave travel
For a uniform plane wave travelling in x-direction, $E_{x} = 0$

Correct Answer : 1,3 and 4 only

Question 48:

Correct Answer : 336

Question 49:

Consider the following statements regarding Computer Architecture:

The advantage with the dedicated bus is a decrease in size and cost
In synchronous timing, the occurrence of events on the bus is determined by the clock
Data bus width decides the number of bits transferred at one time

Which of the above statements are correct?

Correct Answer : 2 and 3 only

Question 50:

Consider the following statements :

Better memory utilization is possible with contiguous allocation using fixed-size pages
Associative memory is used for providing fast access to data stored in cached memory.
Direct mapping of cache memory is hard to implement

Which of the above statements are correct?

Correct Answer : 1 and 2 only

Question 51:

The decimal value 0.5 in IEEE single precision floating-point representation has fraction bits of

Correct Answer : 000....000 and exponent value of -1

Question 52:

What does the following program print? void f

(i n t^{*} p, i n t^{*} q)

{p = q; p_{*} = 2;}

} int i =0,j=1; int main ( )

{f (& i, & j); p r i n t ('' % d % d | n'' . i . j); g e t c h a r (); r e t u r n 0;}

Correct Answer : 0 2

Question 53:

Consider the following set of processes with data thereof as given here:

Process	Arrival time	CPU Burst time
$P_{1}$	0 ms	12 ms
$P_{2}$	2 ms	4 ms
$P_{3}$	3 ms	6 ms
$P_{4}$	8ms	5 ms

An operating system uses the shortest remaining time first scheduling algorithm for pre-emptive scheduling of processes. The average waiting time of the processes is

Correct Answer : 5.5 ms

Question 54:

The length of cable required for transmitting data at the rate of 500Mbps in an Ethernet LAN with frames of size 10,000 bits for signal speed 2,00,000 km/s is

Correct Answer : 2.0 km

Question 55:

Consider the following statements:

System calls provide the interface between a process and the operating system
PERL implementations include direct system call access
System calls occur in different ways depends on the computer is used

Which of the above statements are correct?

Correct Answer : 1,2 and 3

Question 56:

What is the effective access time, if the average page-fault service time is 25 ms, memory access time is 100ns and page fault rate is P?

Correct Answer : 100+24,999,900 x P ns

Question 57:

Consider the function fun I have shown below: int fun 1 (int num) { int count =0; while (num) { count ++; num>>=1; } return (count); } The value returned by fun 1(435) is

Correct Answer : 9

Question 58:

Consider the following statements in the relevant context:

The two types of currents that flow in semiconductor diodes and transistors are dirt and diffusion currents
The junction region is called the depletion region or space-charge region
When currents flow through the diode in forwarding bias, the depletion region current is mostly of 'diffusion' type

Which of the above statements are correct?

Correct Answer : 1 and 2 only

Question 59:

The bandwidth of a control system can be increased by using

Correct Answer : Phase-lead network

Question 60:

Correct Answer : 600

Question 61:

Consider the following statements for a networks graph, if

B_{f}

is its fundamental tie set matrix corresponding to twigs and links, respectively:

$B_{t}$ is a unit matrix
$B_{l}$ s a rectangular matrix
The rank of $B_{f}$ is (b-n-1)

Where b is the number of branches and n is the number of nodes. Which of the above statements are correct?

Correct Answer : None of the above

Question 62:

An ideal operational amplifier is connected as shown in the figure. what is the output voltage

V_{2}

A	$3 V_{1}$	B	$2 V_{1}$
C	$1 V_{1}$	D	$\frac{V_{1}}{3}$

Correct Answer : A

Question 63:

The moderating index of an AM signal is reduced from 0.8 to 0.5. The ratio of the total power in the new modulated signal to that of the original signal will nearly be

Correct Answer : 0.85

Question 64:

The Truth table for the functions

f (A B C D) = \sum_{m} (01, 3, 4, 8, 9) i s

A	B	C	f
0	0	0	W
0	0	1	X
0	1	0	Y
0	1	1	0
1	0	0	Z
1	0	1	0
1	1	0	0
1	1	1	0

Where W, X,Y, Z are given by (d is the complement of D)

Correct Answer : 1, D, d, 1

Question 65:

An 8-bit DAC uses a ladder network. The full-scale output of the converter in percentage and in volts is,respectively

Correct Answer : 0.39% and 39mV

Question 66:

Consider the following statements :

Flash type ADCs are considered the fastest
In successive approximation type ADCs, conversion time depends upon the magnitude of the analogue voltage
Counter slope ADCs are considered the slowest

Which of the above statements are correct?

Correct Answer : 1 and 4 only

Question 67:

For the feedback control system shown, if the steady state error is 20% for the unit step input signal, then the value of K must be

Correct Answer : 4

Question 68:

The closed-loop transfer function

\frac{C (s)}{R (s)}

of the system represented by the signal flow graph as shown in the figure is

A	$\frac{G_{1} G_{2} G_{3} G_{4}}{(1 + G_{1} + G_{2})}$	B	$\frac{G_{1} G_{2} G_{3} G_{4}}{(1 + G_{3} + G_{4})}$
C	$\frac{G_{1} G_{2} G_{3} G_{4}}{(1 + G_{1} + G_{2}) (1 + G_{3} + G_{4})}$	D	$\frac{G_{1} G_{2} G_{3} G_{4}}{(1 + G_{1} + G_{2}) (1 + G_{3} G_{4})}$

Correct Answer : C

Question 69:

For the block diagram as shown in the figure, the overall transfer function

\frac{C}{R}

A	$\frac{G_{1} G_{2} H_{1}}{(1 - G_{1} H_{1} - G_{2} H_{2})}$	B	$\frac{G_{1} G_{2}}{(1 - G_{1} H_{1} + G_{2} H_{2})}$
C	$\frac{G_{1} G_{2}}{(1 + G_{1} H_{1} + G_{2} H_{2})}$	D	$\frac{G_{1} G_{2}}{(1 + G_{1} H_{1} - G_{2} H_{2})}$

Correct Answer : D

Question 70:

The block diagram shows a unity feedback closed-loop system. The steady-state error in the response to a unit step input is

Correct Answer : 57%

Question 71:

The open-loop transfer function of negative feedback is

G (s) H (s) = \frac{K}{s (s + 5) (s + 12)}

For ensuring system stability the gain K should be in the range

Correct Answer : 0

Question 72:

The characteristic polynomial of a feedback control system is given by

R (s) = s^{5} + 2 s^{4} + 2 s^{3} + 4 s^{3} + 11 s + 10

For this system, the numbers of roots that lie in the left hand and right-hand s-plane respectively, are

Correct Answer : 3 and 2

Question 73:

The open-loop transfer function G(s)H9s) of a Bode's plot for feedback system as shown in the figure is

A	$\frac{K (s + 5)}{s^{2} (s + 10)}$	B	$\frac{K (s + 5)}{(s + 10)}$
C	$\frac{K (s + 10)}{s^{2} (s + 5)}$	D	$\frac{K (s + 10)}{s (s + 5)}$

Correct Answer : C

Question 74:

A system with the characteristic equation

s^{4} + 2 s^{3} + 11 s^{2} + 18 s + 18 = 0,

will have closed-loop poles such that

Correct Answer : Two poles lie symmetrically on the imaginary axis of the s-plane

Question 75:

The open-loop transfer function G(s)H(s) of a root locus plot of a system as shown in the figure is

A	$\frac{4}{{(S + 1)}^{1}}$	B	$\frac{4}{{(S + 1)}^{2}}$
C	$\frac{4}{{(S + 1)}^{3}}$	D	$\frac{4}{{(S + 1)}^{4}}$

Correct Answer : B

Question 76:

The transfer function of a compensator is

\frac{(1 + 3 s T)}{(1 + s T)} .

The maximum possible phase shift is.

A	$30 °$	B	$45 °$
C	$60 °$	D	$90 °$

Correct Answer : B

Question 77:

The steady-state response c(t) for an input r(t) =sin 2t to a system transfer function

\frac{1}{s + 4} i s

A	0.25 Sin2t	B	$\sin (2 t - 45 °)$
C	$0.316 \sin (2 t - 26.5 °)$	D	$0.632 \cos 2 t$

Correct Answer : B

Question 78:

Compensation derived from the P-D network whose differential equation is governed by

e_{o} = 20 (e_{1} + T \frac{d e_{i}}{d t})

as shown in the figure is to be investigated. For what value of T will the closed-loop response be critically damped?

Correct Answer : 1.612

Question 79:

The unity feedback system as shown in the figure is characterized by

G (s) = \frac{1}{{(s + 1)}^{2}} .

The output time response will have a damping factor ζ, and natural frequency

ω_{n},

respectively, as

A	0.707 and 1	B	$0.866 a n d \sqrt{2}$
C	$0.707 a n d \sqrt{2}$	D	0.866 and 1

Correct Answer : A

Question 80:

For a state model

\dot{X = A X, w h e r e A = [\frac{1}{1} \frac{0}{1}]}, t h e s t a t e

transition matrix is

A	$[\frac{t e^{- t}}{e^{t}} \frac{0}{e^{t}}]$	B	$[\frac{0}{e^{t}} \frac{t}{t e^{t}}]$
C	$[\frac{e^{- t}}{t e^{t}} \frac{0}{e^{t}}]$	D	$[\frac{t}{t^{2}} \frac{0}{e^{t}}]$

Correct Answer : B

Question 81:

A unit step input to a unity feedback system is shown in the figure, the time for peak overshoot is,nearly

Correct Answer : 0.79 s

Question 82:

The transient response of second-order underdamped system starting from rest is given by

c (t) = A e^{- 6 t} \sin (8 t + θ), t \geq 0 .

The natural frequency of the system is

Correct Answer : 10

Question 83:

For a feedback control system, all the roots of characters equations can be placed at the desired location in the s-plane of only the system is

Observable
Controllable

Which of the above statements are correct?

Correct Answer : Neither 1 nor 2

Question 84:

A second-order system with a zero at -2 has its poles located at -3+j4 and -3-j4 in the s-plane . The undamped natural frequency and the damping factor of the system respectively are

Correct Answer : 5 rad/s and 0.80

Question 85:

What is the error rate factor

K_{e}

to yield a damping factor of 0.5 for the system shown in the block diagram?

Correct Answer : 0.284

Question 86:

Correct Answer : 2100 W

Question 87:

In an induction motor for a fixed speed at constant frequency

Correct Answer : Both line current and torque are proportional to voltage

Question 88:

In a core-type single-phase transformer the steel core is assembled by staggering butt-joints in adjacent layers of laminations vide figures. The purpose served is said to be

Avoiding continuous air-gap
Preventing loss of mechanical strength
Reducing eddy-current loss

Which above the statements are correct?

Correct Answer : 1 and 2 only

Question 89:

Which of the following would refer to an ideal transformer?

Winding resistance is negligible
Leakage-fluxes are included
Core-losses are negligible
Magnetization characteristic is a liner

Correct Answer : 1,3 and 4 only

Question 90:

(ω_{m})

of 183.2 rad/sec, the induced emf in the armature winding is nearly

Correct Answer : 1260V

Question 91:

A 220V dc compound generator connected in long-shunt made has the following parameters:

R_{a} = 0.1 Ω, R_{s h} = 80 Ω, R_{s e r i e s} = 0.05 Ω .

For a load of

150 ∆

at rated terminal voltage, the include emf of the generator should nearly be

Correct Answer : 243V

Question 92:

The Laplace transform of

f (t) = t^{n} e^{- α t} u (t) i s

A	$\frac{(n + 1)!}{{(s + α)}^{n + 1}}$	C	$\frac{n!}{{(s + α)}^{n}}$
B	$\frac{(n - 1)!}{{(s + α)}^{n + 1}}$	D	$\frac{n!}{{(s + α)}^{n + 1}}$

Correct Answer : D

Question 93:

A dc shunt motor has the following characteristics,

R_{a} = 0.5 Ω, R_{f} = 200 Ω,

based speed=1000rpm, rated voltage=250V.On no load, it draws a current=5A. At what speed will this run while delivering a torque of 150N.m?

Correct Answer : 881rpm

Question 94:

The figure shows plots of speed (N) Vs.armature current

(I_{a})

of a motor for two different operating conditions. Which one of the following feature is relevant?

Correct Answer : (1) represents stronger series field and (2) represents stronger shunt field of compound motor

Question 95:

A 230V,50Hz,4-pole,single-phase induction motor is rotating clockwise (forward) direction at a speed of 1425rpm. If the rotor resistance at standstill is 7.8

Ω

, then the effective rotor resistance in the backward branch of the equivalent circuit will be

A	$2.0 Ω$	B	$4.0 Ω$
C	$7.8 Ω$	D	$156 Ω$

Correct Answer : B

Question 96:

Correct Answer : 25kW

Question 97:

When the value of slip of an induction motor approaches zero, the effective resistance

Correct Answer : of the rotor circuit is very high and the motor is under no-load

Question 98:

A4-pole,%50Hz,3-phase induction motor with a rotor resistance of

0.25 Ω

develops a maximum torque of 25N.m at 1400rpm.The rotor reactance

x_{2}

and slip at maximum torque

m_{s} a x, T

respectively would be

A	$2.0 a n d \frac{1}{15}$	B	$3.75 a n d \frac{1}{12}$
C	$2.0 a n d \frac{1}{12}$	D	$3.75 a n d \frac{1}{15}$

Correct Answer : C

Question 99:

Correct Answer : 0.03

Question 100:

Correct Answer : 200V

Question 101:

A 3-MVA,6-pole,50Hz,3-phase synchronous generator is connected to an infinite bus of 3300V; and it is run at 1000rpm. The synchronous reactance of the machine is 0.915

Ω

per phase. The synchronizing torque for

1 °

mechanical displacement of the rotor is

Correct Answer : 6000N.m

Question 102:

The second-harmonic component of the power P versus load angle δ characteristic of a synchronous machine, operating at a terminal voltage

V_{t}

and having the d-and q-axis reactance per phase of

X_{d}

and

X_{q}

,respectively ,is

A	$\frac{V_{t}^{2}}{2} . \frac{X_{d} X_{q}}{X_{d} + X_{q}} \sin 2$ δ	B	$\frac{V_{t}^{2}}{2} (\frac{1}{X_{q}} - \frac{1}{X_{d}}) \sin 2$ δ
C	$\frac{V_{t}^{2}}{2} . \frac{X_{d} X_{q}}{X_{d} + X_{q}} \cos 2$ δ	D	$\frac{V_{t}^{2}}{2} (\frac{1}{X_{q}} - \frac{1}{X_{d}}) \cos 2$ δ

Correct Answer : B

Question 103:

The term Synchronous condenser refers to

Correct Answer : An over-excited synchronous motor operating at no-load with leading power factor used in large power stations for improvement of power factor

Question 104:

Which of the following operating aspects necessitating the computation of Regulation of an alternator?

When the load is thrown off
For designing an automatic voltage-control equipment
For determination of steady-state and transient stability
For parallel operation of alternators

Correct Answer : 1,2,3 and 4

Question 105:

A 2 phase ac servomotor has a tendency to run as a single-phase induction motor if the voltage across the control winding becomes zero. To prevent this

Correct Answer : Drag-cup type of light rotor and high resistance is to be used

Question 106:

A single-stack,8-phase(stator),multiple-step motor has 6rotor teeth.The poles are excited one at a time. If the excitation frequency is 120 Hz,the speed of the motor is

Correct Answer : 5 rps

Question 107:

An extra-high voltage transmission line of length 3001cm can be approximated by a lossless line having propagation cottage

β

=0.00127 rad/km. The percentage ratio of line length to wavelength will nearly be

Correct Answer : 6%

Question 108:

A lossy capacitor

C_{x},

rated for the operation of 5kV,50Hz is represented by an equivalent circuit with an ideal capacitor

C_{p}

in parallel with a resistor

R_{p} . C_{p}

is 0.102

μ F;

and

R_{p} = 1.25 M Ω .

The power loss, and tanδ, of the lossy capacitor, when operating at the rated voltage are respectively

Correct Answer : 20 W and 0.025

Question 109:

The time interval needed for a surge to travel to the end of a 600 km long overhead transmission line is

Correct Answer : 2 ms

Question 110:

At what power factor will a lossless line with a reactance of 0.6 exhibits zero regulation given that the sending end voltage is 1.0 up?

Correct Answer : 0.954 lead

Question 111:

An 11 kV,3-phase transmission line has a resistance of 1.5 Ω and reactance of 4 Ω per phase. The efficiency of the line when supplying the load of 4 MW at 0.8 lagging power factor is nearly

Correct Answer : 92%

Question 112:

The dielectric loss in the insulation of a lossy underground cable, due to leakage current is (using standard notations)

A	$ω C V^{2} C o s$ δ	B	$ω C V \tan$ δ
C	$ω C V^{2} \tan$ δ	D	$ω C V \sin$ δ

Correct Answer : C

Question 113:

A 3-phase, 100 MVA,11 kV generator has the following p.u constants. The generator natural is solidly grounded.

X_{1} = X_{2} = 3 X_{0} = 0.15 Ω

. The ratio of the fault current due to three-phase dead-short-circuit to that due to L-G fault would be nearly

Correct Answer : 0.78

Question 114:

A	$14.4 ∠ + 30 ° A$	B	$25.0 ∠ + 30 ° A$
C	$14.4 ∠ - 30 ° A$	D	$25.0 ∠ + 30 ° A$

Correct Answer : C

Question 115:

In a circuit-breaker, the are is produced due to

Thermal emission
The high temperature of the air
Field emission

Which of the above statements are correct?

Correct Answer : 1 and 2 only

Question 116:

The line reactance of a power network is as follows:

Line No.	From Bus	To Bus	Reactance
1	0	1	0.2 p.u
2	1	2	0.4 p.u

The bus impendence matrix with '0' as ref-bus is

A	$[\frac{0.2}{0.4} \frac{0.4}{0.6}]$	B	$[\frac{0.4}{0.2} \frac{0.2}{0.6}]$
C	$[\frac{0.2}{0.2} \frac{0.2}{0.6}]$	D	$[\frac{0.6}{0.2} \frac{0.2}{0.4}]$

Correct Answer : C

Question 117:

An alternator is

Correct Answer : A polyhase synchronous machine operated with DC exciter

Question 118:

The stability of a system, when subjected to a disturbance, is assessable by which of the following methods?

Swing curve
Equal-area criterion
Power-angle diagram
Power-circle diagram

Correct Answer : 1,2 and 3 only

Question 119:

Power transmission capacity of a high voltage line can be increased by

Correct Answer : Reducing the effective series reactance of the line

Question 120:

A 40MVA,11kV,3-phase,50Hz,4-pole turbo-alternator has an inertia constant of 15sec.An input of 20MW developed 15MW of output power (Neglecting losses). Then the accelerations are

A	$60 ° / s^{2}$	B	$65 ° / s^{2}$
C	$70 ° / s^{2}$	D	$75 ° / s^{2}$

Correct Answer : D

Question 121:

In a Progressive Simplex Lap Winding for a 4-pole,14-slot,2 coil-siders per slot d.c armature, the back pitch

y_{b}

and front pitch

y_{f}

will be respectively

Correct Answer : 7 and 5

Question 122:

The starting current in an induction motor is 5 times the full-load current while the full load slip is 4% The ratio of starting torque to full-load torque is

Correct Answer : 1.0

Question 123:

When a bundle of conductors are used in place of single conductors the effective inductance and capacitance will,respectively

Correct Answer : Decreases and increase

Question 124:

A buck regulator has an input voltage of 12V and the required output voltage is 5V.what is the duty cycle of the regulator?

A	$\frac{5}{12}$	B	$\frac{12}{5}$
C	$\frac{5}{2}$	D	$6$

Correct Answer : A

Question 125:

Correct Answer : Statements (I) is true; but statements (II) is false

Question 126:

I_{1} a n d I_{2}

cannot be connected in series. Statements (II): Superposition Theorem cannot be applied to current sources when one terminal of each of these sources is connected to a common node.

Correct Answer : Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Question 127:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Both Coupling capacitance and Emitter bypass capacitance affect the low-frequency response of an R-C-coupled amplifier Statements (I): Both stray capacitances and Emitter-to-base diffusion capacitance have a profound effect response of an R-C-couple amplifier.

Correct Answer : Statements (I) is true; but statements (II) is false

Question 128:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A ' bedding' is provided over to the metallic sheath in an underground cable Statements (I): The bedding protects the metallic against corrosion

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 129:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Zero-sequence currents are, by definition in phase with each other in the three windings of any three windings of any three-phase apparatus Statements (I): They may be caused by magnetic saturation in the transformers.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 130:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): 'High resistance' method is used for our extinction in DC circuit breakers. Statements (I): Very little energy is dissipated in the arc in the high resistance method of arc extinction.

Correct Answer : Statements (I) is true; but statements (II) is false

Question 131:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A radial main system, circuit experience low voltage at the far end under heavy load conditions Statements (I): The voltage at the far end under heavy loading can be corrected by connecting a shunt capacitor compensator there.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 132:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): In an HVDC system, the steady-state power transfer from a generator to the infinite bus is dependent on the power angle and the line impedance intervening between them. Statements (I): In an HVDC system, the power transfer between the two stations connected by a dc link is much than that in a corresponding EHV ac system.

Correct Answer : Statements (I) is false ; but statements (II) is true

Question 133:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Conventional diode rectifier circuit have low-frequency harmonics. Statements (I): Passive techniques used to reduce the current THD in conventional rectifiers require large transformers and/or reactors.

Correct Answer : Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Question 134:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Resonant inverters are used as electronic ballasts for gas discharge lamps, induction heating etc. Statements (I): A DC to high-frequency AC resonant inverter may be obtained by applying the square wave voltage obtained from a DC source and switch network operating frequency

f_{s}

to a tuned tank circuit designed for frequency

f o

, so as to obtain variable magnitudes of v(t) and i(t) by matching

f_{s} a n d f_{0} .

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 135:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): In liner commutation, the magnitude of the current in the coils under each pole in a DC generator and a given load remains constant. Statements (I): The magnitude of the emf induced in the coils under each pole of a DC generator on load remains constant .

Correct Answer : Statements (I) is true; but statements (II) is false

Question 136:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A very efficient method of speed control of an induction motor is to vary both V and f in such a way that

\frac{V}{f}

the ratio remains constant. Statements (I): Keeping

\frac{V}{f}

constant allows the magnetic flux to remain constant and a reduced V reduces the inrush of starting current.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 137:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Windings of most power transformers are immersed in a tank of oil. Statements (I): Convection currents in the insulting oil help carry the heat away from the windings and the core.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 138:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A large gate pulse is required to turn on a GTO thyristor. Statements (I): This thyristor does not need a commutation circuit.

Correct Answer : Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Question 139:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): The decimal to-BCD encoder digital logic circuit chip IC 74147, is a priority encoder. Statements (II): In this circuit, priority is given to the lowest-order input.

Correct Answer : Statements (I) is true; but statements (II) is false

Question 140:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Analog to digital conversion is essentially a sampling process. Statements (I): Ahold elements are digital to analogue converter.

Correct Answer : Both statements (I) and statements (II)are individually true; but statement (II) is NOT the correct explantion of statement(I)

Question 141:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): High-level programming languages preferred by the scientific community as they are user friendly Statements (I): High -level programming languages provide ways of detailing instruction for problem-solving that are translated into the low-level language via compilers and interpreters before being executed by the computer.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 142:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): The conductivity of an intrinsic semiconductor increases exponentially with temperature. Statements (I): As the temperature rises, more and more covalent bonds are broken resulting in more electron-hole pairs.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 143:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Light is capable of transferring electrons to the free-state inside a material, thus increasing the electrical conductivity of the material. Statements (I): The increased electrical conductivity produced by light is called photo-conductivity.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 144:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A general-purpose dynamometer type wattmeter does not accurately at low power factors. Statements (I): The presence of self-inductance of the pressure coil introduces an error.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 145:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): A dynamometer type wattmeter has a linear scale while a dynamometer type voltmeter has a non-liner scale. Statements (II): Deflecting torque developed in a dynamometer type wattmeter is proportional o the power and that developed in a dynamometer type ammeter is proportional to the square of the current.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 146:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): The rating disc in an energy meter is made of a magnetic material. Statements (II): Braking takes place due to the eddy current generated by the braking magnet.

Correct Answer : Statements (I) is false ; but statements (II) is true

Question 147:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): When a solid surface is bombarded by electrons of appreciable energy, secondary emission occurs from the surface. Statements (I): The major application of the secondary emission is in voltage amplification.

Correct Answer : Statements (I) is true; but statements (II) is false

Question 148:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Electromagnetic flowmeter is preferred for flow velocity measurement of slurries in pipes as long as the slurry has adequate electrical conductivity. Statements (II): Electromagnetic flow meter does not insert any instrument parts into the fluid flow to cause an obstruction as in most other flowmeters.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 149:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Direct access method is based on a disk model of a file. Statements (II): Disks allow random access to any file block.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

Question 150:

The following question consists of two statements one labelled as "statements (I) and the other as statements (II) Examine these two statements carefully and select the answers to these items using the codes given below: Statements (I): Variables that are defined inside subprograms are local variables. Statements (II): Their scope is in the body of the subprogram in which they are defined.

Correct Answer : Both statements (I) and statements (II)are individually true; and statement (II) is the correct explanation of statement(I)

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UPSC | 2018 | Engineering Services (Preliminary) Examination | Electrical Engineering | Practice Online

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