B.KANNAN M.Sc., B.Ed., PH: 7871748594

STD: XII PADASALAI CENTUM COACHING TEAM SPECIAL TEST MARKS:150

SUBJECT : PHYSICS TIME : 3HRS

I.CHOOSE THE CORRECT ANSWER 30X1=30

1. The capacitance of a conductor is

a) directly proportional to the charge q given to it b) inversely proportional to its potential V

c) directly proportional to charge q and inversely proportional to its potential to its potential V

d) independent of charge q and potential V

2. The number of lines that radiate outward from one micro coulomb of charge is

a) 1.12910 b) 1.1310 c) 910 d) infinite

3. The capacitance of a parallel plate capacitor increases from 5 F to 60 F when a dielectric is filled between the plates. The value of dielectric constant is

a) 8.85410 CNm b) 8.85410 CNm c) 12 d) 10

4. The electric field intensity is 100 V/m at a distance of 2 m from a point charge, it will be 400 V/m a

distance of

a) 50 cm b) 4 cm c) 4 m d) 1 m

5. If copper wire of radius r has a certain resistance R, then on doubling the length its resistance

a)will be doubled b)will become 42 times c)will be come 4 times d)will remain the same

6. In a T.G. a current 1A produces a deflection of 30.The current required to produce a deflection of 60

a)3 A b)2 A c)3 A d)1/3 A

7. Of the following which has small resistance?

a) Voltmeter b) ammeter of the range 0-1A

c) moving coil galvanometer d) ammeter of the range 0-10 A

8. In RLC circuit at resonance

a) current is maximum b) impedance (Z) is minimum

c)0=1/2 d) all the above

9. An AC of 5 A produces the same heating effect as a DC of

a) 50 A rms current b) 5 /2 peak current c) 52 A rms current d) none of these

10. The area of a coil of cross section 0.5 m2 with 10 turns is in a plane which is perpendicular to a

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uniform magnetic field of induction 0.2 Wb/m2 . The magnetic flux through the coil

a) 100 Wb b) 10 Wb c) 1 Wb d) zero

11. Which of the following devices does not allow dc to pass through

a)capacitor b) inductor c) resistor d) all the above

12. In Newton's ring experiment the radii of mth and (m+3)th dark rings are respectively 3 mm and 6 mm What is the value of m?

a) 1 b) 2 c) 4 d) 8

13. Electromagnetic waves are

a)transverse b)may be longitudinal or transverse

c)longitudinal d)neither longitudinal nor transverse

14. In an electromagnetic wave the phase difference between the electric field E and the magnetic

field B is

a)

4 b)

2 c) d) zero

15. The nature of wave front corresponding to extraordinary ray inside a calcite crystal is

a) plane b) spherical c) elliptical d) cylindrical

16. According to Bohr's postulates which of the following quantities takes discrete values?

a) kinetic energy b) potential energy c) angular momentum d)momentum

17. In hydrogen atom which of the following transition produces maximum frequency

a) 2 1 b) 6 2 c) 4 3 d) 5 1

18. The ionisation potential of hydrogen atom is

a) 13.6 eV b) -13.6 eV c) 13.6 V d) -13.6 V

19. Chromium ions doped in the ruby rod

a)absorbs red light b)absorbs blue light

c)absorbs green light d)emits green light

20. The momentum of the electron having wavelength 1A0 is

a) 3.31024 kgms-1 b) 6.61024 kgms-1 c) 3.310-24 kgms-1 d) 6.610-24 kgms-1

21. When a material particle of mass 'm0' attains the velocity of light, its mass becomes

a) zero b)2m0 c)4m0 d)infinity

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22. One amu is equal to

a) 931 eV b) 14.9410-10 J c)1.49410-10 J d) 931 J

23. The half-life period of N13 is 10.1 minutes. Its mean life time is

a) 5.05 minutes b) 20.2 minutes c) 14.57 minutes d) infinity

24. Anemia can be diagnosed by

a) 15P31 b) 15P32 c)26Fe59 d) 11Na24

25. Arrange the , rays in the decreasing order of their ionizing power

a) , , b) , , c) , , d) , ,

26. In reverse bias characteristic curve , the diode appears as

a) a high resistance b) a capacitor c) an OFF switch d) an ON switch

27. The electrons in the atom of an element which determine its chemical and electrical properties are

called

a) valence electrons b) revolving electrons c) excess electrons d) active electrons

28. Avalanche breakdown is primarily dependent on the phenomenon of

a) collision b) ionization c) doping d) recombination

29. High frequency waves follow

a) the ground wave propagation b) the line of straight line direction

c) the ionospheric propagation d) the curvature of the earth

30. In FM signals has a resting frequency of 105 MHZ when modulated by a signal 105.03 MHZ . The frequency deviation is

a) 0.03 MHZ b) 60 KHZ c) 60 MHZ d) 0.03 KHZ

II. ANSWER ANY 15 QUESTIONS 15X3=45

31. Define Coloumb on the basis of coloumbs law.

32. Distinguish Polar and Non-Polar molecules.

33. Why is copper wire not suitable for a potentiometer?

34. Two wires of same material and length have resistances 5 and 10 respectively. Find the ratio of radii of the two wires.

35. What are the applications or advantages of secondary cells?

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36. State Amperes circuital law.

37. Define Quality factor.

38. Write the equation of a 25 cycles current sine wave having rms value of 30 A.

39. In sunset and sun shine the sky looks reddish why?

40. In Newtons rings experiment the diameter of a certain order of dark ring is measured to be double that of second ring . What is the order of the ring?

41. Write the principle of Millikans Oil drop experiment. 42. Find the maximum frequency of X-rays produced by an X-ray tube at 1000KV. 43. State the postulates of special theory of relativity. 44. Write any 3 conclusions from binding energy curve. 45. The distintegration constant of radioactive element is 0.000231 / day. Calculate its mean life. 46. Draw the circuit for summing amplifier using operational amplifier. 47. Distinguish between Avalanche breakdown and Zener breakdown. 48. What is an Intrinsic semiconductor? Give examples. 49. In a common base transistor circuit IC=0.97 mA and IB= 30 A. Calculate the value of . 50. What is meant by Skip distance?

III.i) Answer Q.No:58 compulsorily.

ii) Answer any 6 of the remaining 11 questions 7X5=35

51. Derive an expression torque experienced by an electric dipole placed in a uniform electric field.

52. Define mobility. Establish the relation between drift velocity and current.

53. Explain the method of compare the emfs of two cells using potentiometer.

54. 16 revolutions per second.

Determine the magnetic moment associated with orbital motion of the electron.

55. Obtain an expression for the current flowing in a circuit containing resistance only to which

alternating emf is applied. Find the phase relationship between voltage and current.

56. Write a note on Nicol prism.

57. Mention any five properties of X-rays.

58. a) The time interval measured by an observer at rest is 2.5 x 10-8 s What is the time interval as

measured by an observer moving with velocity v=0.73C (OR)

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b) A metallic surface when illuminated with light of wavelength 3333 emits electrons with energies

upto 0.6 eV. Calculate the work function of the metal

59. Establish Einstein `s mass energy equivalence E=mc2

60. Show that the mass of radium (88Ra 226) with an activity of 1 curie is almost a gram.(1 curie =3.7X1010

disintegration per second)

61. Explain the working of a half wave diode rectifier .

62. What are the advantages and disadvantages of digital communication?

IV. i) Answer any 4 questions in detail ii) Draw diagrams wherever necessary. 4X10=40

63. State Gausss law. Applying this, calculate electric field due to charged spherical shell i) inside

the shell ii) on the shell iii) outside the shell

64. Deduce an expression for the magnetic induction due to an infinitely long straight conductor carrying

current.

65. Explain in detail the principle, construction and theory of a transformer. Define its efficiency. Mention the losses

66. Explain Raman scattering with the help of energy level diagram

67. Describe the J.J. Thomson method to determine the specific charge of electron

68. State the radioactive law of disintegration. Obtain an expression to deduce the amount of the radioactive substance present at any instant. Obtain the relation between half life period and decay constant.

69. Sketch the circuit of Colpitt s oscillator and explain its working

70. Make an analysis of amplitude modulated wave. Plot the frequency spectrum.

ALL THE BEST

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