Solved question paper for Physics Mar-2017 (PSEB 12th)

Question paper 1

1. 1. The specific resistance of a conductor increases with

   (a) Increase in temperature.

   (b) Increase in closs-sectional area.

   (c) Decrease in length

   (d) Decrease in cross-sectional area.

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2. 2. Write whether the given staternerrt is true or false : The magnetic susceptibility  X_m of a paramagnetic substance  has a small neagtive value.

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3. 3. Name the three basic elements of a communication system

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4. 4. Which has greater ionising power : alpha particle or beta particle ?

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6. 5. Write the following radiations in an ascending-order in respect of their frequencies : X-rays, microwaves, UV (ultra-violet) rays and radio wave.

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7. 6. State Lenz's law of electromagnetic induction

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8. 7. A wire has a resistrince of 10.5\(\Omega\) at 21'C and 16.4\(\Omega\) at 147'C. Find the value of temperature coefficient of resistance

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9. 8. What type of magnetic material is used in making electromagnets and why ?

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11. 9. An induced current has no direction of its own. Explain, why ?

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12. 10. The small ozone layer on top of the stratosphere is crucial for human'survival. Why ?

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13. 11. Write the conditions for total internal reflection to take place.

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14. 12 ln\bung's double slit experiment, the slits are separated by 0.55mm and the screen is placed Z.hmaway. The distance between the central bright fringe and the fifth bright fringe is 1.5cm. Find the wavelength of lightused.

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16. 13. For a common emitter amplifier, dc (direct current) current gain is 100. If the base current is 20 uA, calculate the colleetor ahd emitter current

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17. 14. Why sky wave propagation is not possible for high frequency radio waves ?

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18. 15. Derive an expression for energy stored in a capacitor. In which form energy is stored ?

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19. 16. With the help of a circuit diagram, explain how a metre bridge can be used to find the unknown resistdence of a given wire.

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21. 17. Derive an expression for average power of an AC (atternating current) circuit

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22. 18. What is photoelectric effect ? Explain the effect of increase of' (i) frequency (ii) intensity of incident radiation on photoelectric current with suitable graphs

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23. 19. Light of wavelength2200 A (angstorm) falls on a photosensitive plate with work function 4.1 eV. Find (a) energy of photon in eV (electron volt), (b) maximum kinetic energy of photoelectron and (c) stopping potential.

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24. 20. State radioactive decay law. Prove that radioactive decay is exponantial in nature? 

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26. 21. With the help of circuit diagram, explain the V-I characteristics ofp-n junction diode in forward biasing

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27. 22. State Huygens'principle. Using Huygens'wave theory prove the laws of reflection.

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28. 23. (a) Which physical quantity has its SI unit (1) Cm (2) N/C

    (b) Two point charges q and -q is placed at a distance 2a apart.Calculate the electric field at a point P situated at a distance r along the prependicular bisector of the line joining the charges. What is the electric field when r >> a ? also, give the direction of electric field w.r.t. electric dipole moment ?

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29. 24. (a) A charged rod P attracts rod R whereas P repels another charged rod Q. What type of force ' is developed between Q and R ?

    (b) Define the capacitance of capacitor. Derive an expression forthe capacity of a parallel plate capacitor with a dielectric slab placed in between the plates of capacity.

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31. 25. (a) What is shunt ?

    (b)  State Ampere's circuital l'aw. Using this law, obtain an expression for the magnetic field well inside the solenoid of finite length

    or 

    (a) Define one tesla. 

    (b) Derive an expression for force experienced bya current carrying straight conductor placed in a magnetic field. How can we find the direction of force ?

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32. 26. (a) what are charact6ristics of image formed by aplane mirror ?

    (b) By giving sign conventions made, derive the mirror formula for a concave mirror

    or

    (a) what is least distance of distinct vision for a normal human eye ?

    (b) With the help of labelled diagram, give the principle and magnifying power of astronomical teleScope, when final image is,formed at least distance of distinct vision.

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Question paper 2

1. 1. A fuse wire is a wire of

   (a) Both low resistance and low melting point.

   (b) High resistance and low melting point.

   (c) Low resistance and high metting point.

   (d) Both high resistance and high melting point.

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2. 2. Write whether the given statement is true or false : A diamagnetic substance is feebly attracted by a magnet.

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3. 3. Among (alpha), (Beta) and (gamma) radiations, which one is not affected by magnetic field ? 

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4. 4. Define the SI unit of self-inductance.

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6. 5. What is function of transducer ?

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7. 6.  Write the following radiations in a descending order of their frequencies red light, X-rays, microwaves, radio-waves

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8. 7. A resistance of a tungsten filament at 150"C is 133\(\Omega\). What will be its resistance at 500"C ? The temperature coefficient of resisiance of tungsten at 0"C is 0.0045 "C-1

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9. 8. Which material is preferred for making permanent niagnets ? Give reason for your choice ?

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11. 9. Why is the coil of a dead-beat galvanometer wound on a metal frame ?

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12. 10. Microwaves are used in RADAR why?

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13. 11. Define (i) critical angle (ii) polarising apgle

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14. 12. For a common emitter, amplifier dc (direct current) current gain is 60. If the emitter current is 6.6 mA, calculate the collector and base current

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16. 13. Whatis space wave propagation ? Give one example of communication system, which use space wave mode.

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17. 14. what is the focal length of the combination of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 em? rs the system a converging or diverging lens ? Ignore thickness of the lenses.

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18. 15. Derive an explession for the capacitance of parallel plate capacitor when a dielectric slab is introduced between the plates of capacitor.

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19. 16. what is the principle of a potentiometer ? with the helpof circuit diagram, explain the use of  potentiometer measure internal resistance of given primary cell

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21. 17. Give the principle of a transforrner, construction of a step-down tiansformer. energy losses of a transformer.

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22. 18. State the laws of photoelectric emission.

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23. 19. With the help of circuit diagram, explain the working of npn transistor as an amplifier in commohn ernitter configuration.

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24. 20. Draw the graph showing variation of binding energy per nucleon with mass number.write the inferences drawn from the graph.

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26. 21. (a) What would be the work done, if a point charge '+q' is taken from,,a point A to a point B on the circumference of a circle drawn with another point charge +q at the centre ?

    (b) State Gauss's theorcm in electrostatics. Using Gauss's theorem in electrsstatics, derive an expression for electric field intensity at a point due to infinite sheet of charge. How does the electrjs field change for a thick sheet of charge ?

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27. 22. (a) Define the SI unit of electric charge.

    (b) Two point charges q and - q is placed at a distance  apart.Calculate the electric field at a point P situated at a distance r along the axial line of an electric dipole. What is the electric field when r >> a ? Also, give the direction of electric^ field w.r.t. electric dipole moment.

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28. 23. (a) State the rule that is used to find the direction of field acting at a point near a current carrying straight conductor.

    (b) State Ampere's circuital law Using this law obtain an expression for the magnetic field duc to an infinitely long wire carrying current.

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29. 24. (a) An electric charge enters in electric field at right angles io the direction of electric fietd. What is the nature of the path followed?  

    (b) With the help of labelled diagram, give the principal, construction and theory of cyclotron.

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31. 25. (a) Define power of a lens.

    (b) By giving assumptions made, derive the lens maker formula for a double convex lens.

    or

    (a) What are coherent sources of light ?

    (b) State the necessary conditions for su-stained interference pattern. Derive an expression for the fringe width using Young's double slit method for interference of light

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Question paper 3

1. 1. One kilowatt hour is equal to

   (a) 36x1O⁵J

   (b) 36 x10³J

   c) 36 x10^-5J

   (d) 3.6 x 10^-6J

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2. 2. The output of OR gate is 1

   (a) if either input is zero

   (b) if both inputs are zero

   (c) only, if both inputs are 1

   (d) if either or both inputs are 1.

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3. 3. The de-Broglie wave coriesponding to aparticle of mass 'm' and.velocity 'v' has  a wavelength associated with it.

   (a) \(h\over mv\)     (b) hmv

   (c)  \(mh\over v\)     (d) \( h\over \sqrt{mv}\)

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4. 4. Write wether the given statement is true or false: the diamegnetic substances obeys curies law

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6. 5. Among (alpha), (beta) and (gamma) rays which one has highest penetrating power ?

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7. 6. What is audible range for normal human being ?

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8. 7. Arra+ge the following radiations in the degcending order of wavelength : X-rays, radio waves, , yellow light, infra-redrays

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9. 8. What is meant by magnetic flux ?

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11. 9. A silver wire has a resistance of 2.1\(\Omega\) at 27.5"C and a resistance.of 2.7\(\Omega\)  at 100"C . Determine the temperature coefficient of resistance of silver

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12. 10.Why soft iron is used in making the core of a transformer ?

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13. 11. Self-induction is called the inertia of electricity. Explain, why ?

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14. 12. Give two properties of electromagnetic waves ?

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16. 13. Give two points of difference between interference and diffraction

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17. 14. In Young's double slit experiment, the slits are separated by 0.28 mm and the screen is placed 1.4 m away. The distance between the central bright frirye,and the fourth bright fringe is 1.2 cm. Find the wavelength if light used

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18. 15. For a common emitter ,amplifier, dc (direct current) current gain is 20. If the emitter current is TmA,calculate the base and collector current .

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19. 16. Write any two factors, which justify the need of modulation for the transmission of the audio signal

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21. 17. Derive an expression for electric potential'at anypoint due to an electric dipole. Show that the potential at a point on the equatorial line of an electric dipole is zero

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22. 18. Draw the circuit diagram of a Wheatstone bridge use Kirchhoff's law to obtained the balance condition of Wheatstone bridge

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23. 19. Draw a labelled diagram of anAC (alternating current) generator. Give its principle and working of an AC (alternating current) generator.

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24. 20. Explain the laws of photoelectric emission on the basis of Einstein's photoelectric equation.

     or

    Light of wavelength 5000 A falls on a photosensitive plate with work ,function 1.9 eV. Find (a) energy of photon in eV (electron volt), (b) maximum kinetic energy of photoelectron and (c) stopping potential

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26. 21.  What are drawbacks of Rutherford's atomic model ? How did Bohr remove these ?

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27. 22. What is rectifier ? Explain with the help of circuitdiagram,ths working of p-n junction diode as a full wave rectifier?

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28. 23. Derive the mirror formula using the ray' diagram for the formation of a real image by a concave mirror

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29. 24. (a) What do you mean by accommodation ?

    (b) Draw a labelled diagram of human eye. What is myopia and hypermetropia ? How the eyes of a person suffering from these defects may be corrected ?

    or

    (a) State Snell's law of refraction of light

    (b) With the help of labetled diagram, give the principle and magnifying power of compound microscope, when final image is formed at least distance of distinct vision.

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31. 25. (a) An electric dipole consisting of charge 5pC and -5pC and of length 10 cm. What is the total electric flux through the box ?

    (b) State Gauss's theorem in elecfostatics. Apply this to derive an expression for electric field intensity due to a uniformly eharged hollow sphere (i) at a point inside the sphere (ii) at a point outside the sphere.

    or

    (a) Define the SI unit of capacitance.

    (b) With the help of labelled diagram, give the principle, construction and working of Van de Graffgenerator

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32. 26. (a) State Maxwell's cork screw rule

    (b) State Biorsavart law. Using Biot-Savart law find the magnitude and direction of magnetic field at a point on the axis of a circular coil of radius 'r', number of turns 'N' carrying current'

    or

    (a) What is radial magnetic field ?

    (b) With the help of labelled diagram, give the principle, construction and theory of moving coil galvanometer.

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