Possible Five mark Questions


1.      Derive an expression for the capacitance of a parallel plate capacitor with a dielectric between the plates.

2.      State and explain Coulomb’s Inverse square law in electrostatics.

3.      Derive an expression for the torque on an electric dipole in an electric field.

4.      State the properties of electric lines of forces.

5.      +q and -3q are separated by 1m. At which point between the charges on its axial line the potential is zero? ( OR ) A parallel plate capacitor with air between the plates has a capacitance of 8 pF. What will be the capacitance, if the distance between the plates be reduced to half and the space between the plates is filled with a substance of dielectric constant 6 ?

6.      Derive an expression for the electric potential at any point due to a point charge.

7.      Derive an expression for the energy stored in a capacitor.

8.      Explain the action of lightning conductor.

9.      Explain the action of Lead acid accumulator.

10.  Explain the principle of the potentiometer.

11.  Derive the relation between current and drift velocity.

12.  The effective resistances of two resistances are 10 Ω and 2.4 Ω when they are connected in series and parallel. What are the individual resistors ?

13.  The resistance of a coil is 50 Ω at 200 C and 65 Ω at 700 C. Find the temperature coefficient of resistance.

14.  Explain the working of Leclanche cell.

15.  Explain the method to find the resistance of a wire using the metre bridge.

16.  Explain the method to compare the emf’s of the two cells using the potentiometer. 15. State and explain Faraday’s laws of electrolysis.

17.  Derive condition for bridge balance of a Wheatstone’s bridge.

18.  Explain the construction and working of Daniel cell.

19.  Explain Positive Thomson effect.

20.  Explain the conversion of galvanometer into voltmeter.

21.  Derive an expression for the force on a current carrying conductor in a magnetic field.

22.  Write a short notes on voltage sensitivity of a galvanometer.

23.  A current of 4 A flows through 5 turns coil of a TG having a diameter of 30 cm. If the horizontal component of the

24.  Earth’s magnetic induction is 4 X 10 -5 T, find the deflection produced in the coil.

25.  A galvanometer has a resistance of 100 ohm. A shunt resistance of 1 ohm is connected across it. What part of the total current flows through the galvanometer ?

26.  Write a short notes on Thermopile.

27.  Explain the method of inducing an emf by changing the area enclosed by a coil.

28.  Derive an expression for the energy associated in an inductor.

29.  Explain the various forms of energy losses in a transformer.

30.  Explain the construction and working of a choke coil.

31.  Explain the formation of eddy currents.

32.  Write a short notes on transformers.

33.  A solenoid of length 1m and 0.05 m diameter has 500 turns. If a current of 2 A passes through the coil, calculate the co-efficient of self induction of the coil.

34.  A transformer has an efficiency of 80%. It is connected to a power input at 4kW and 100 V. If the secondary voltage is 240 V, calculate the primary and the secondary currents.

35.  Explain the construction and the working of Nicol prism.

36.  Explain Young’s double slit experiment.

37.  Explain the corpuscular theory of light.

38.  Explain Raman effect.

39.  Using Huygen’s principle, explain the method of obtaining the position of a new wavefront.

40.  In Newton’s ring experiment the diameter of the 20th dark ring was found to be 5.82 mm and that of the 10th ring 3.36 mm. If the radius of the plano- convex lens is 1 m. Calculate the wavelength of the light used.

41.  A parallel beam of monochromatic light is allowed to incident normally on a plane transmission grating having 5000 lines per centimeter. A second order spectral line is found to be diffracted at an angle 300. Find the wavelength of the light used.

42.  State and explain Bragg’s law.

43.  Explain the action of the Ruby laser.

44.  Explain the various types of the spectral series of the hydrogen atom.

45.  Explain the construction of the discharge tube.

46.  Calculate the closest approach of α - particle to the copper nucleus when α – particle of 5 MeV is scattered back by a thin sheet of copper. ( Z of copper is 29 ) ( OR ) Monochromatic X – rays of wavelength 1 A o when falls on a crystal, successive reflections take place at angles 30 o and 45 o respectively. Find the lattice constant of the crystal

47.  Explain the variation photo electric current with the applied voltage.

48.  Explain Einstein’s theory of photoelectric effect.

49.  Explain length contraction.

50.  Write a short notes on time dilation.

51.  The time interval measured by an observer at rest is 2.5 X 10 -8 s. What is the time interval as measured by the observer moving with a velocity v = 0.73 C.

52.  Lithium has a work function of 2.3 eV. It is exposed to light of wavelength 4.8 X 10 -7 m. Find the maximum kinetic energy with which the photoelectron leaves the surface.

53.  Derive an expression for de Broglie waves.

54.  Explain the construction and working of an electron microscope.

55.  Derive Einstein’s mass energy equivalence.

56.  Explain the construction and the working of a photo emissive cell.

57.  State any five uses of the photo electric cells.

58.  State the laws of photoelectric emission.

59.  Explain the BE / A curve.

60.  Explain Soddy-Fajan’s radioactive displacement law.

61.  Explain the construction and the working of Geiger-Muller counter.

62.  Explain how carbon-nitrogen cycle can account for the production of stellar energy.

63.  A reactor is developing energy at the rate of 32 MW. Calculate the required number of fissions per second of 92 U 238 . Assume that energy per fission is 200 MeV.

64.  Explain the working of half wave rectifier .

65.  Explain the action of OP – AMP as difference amplifier.

66.  Explain N- type semiconductor.

67.  Explain the working of a transistor amplifier.

68.  The gain of the amplifier is 100. 5% of the output voltage is fed back into the input through a negative feedback network. Find the voltage gain after feedback .

69.  Explain the reflection of electromagnetic waves by the ionosphere.

70.  Explain the amplitude modulation.

71.  Explain the frequency modulation.

72.  Write a short notes on FAX.

73.  In a broadcasting studio, a 1000 kHz carrier is modulated by an audio signal of frequency range 100 – 5000 Hz. Find ( i ) maximum and minimum frequencies of USB, ( ii ) maximum and minimum frequencies of LSB and ( iii ) width of the channel.