12TH STANDARD PHYSICS Prepared by: R.RAJENDRAN,M.A., M.Sc.,M.Ed., N.INGARAN,M.Sc.,M.Phil.,M.Ed., Electromagnetic waves and wave optics

1. Electromagnetic waves are discovered by a) Planck b) J.C.Maxwell c) Newton d) Huygens CHOOSE THE CORRECT ANSWER

2. An accelerated charge is a source of a) electromagnetic radiation b) heat radiation c) mechanical waves d) longitudinal waves CHOOSE THE CORRECT ANSWER

3. Electromagnetic waves are in nature. a) mechanical waves b) longitudinal waves c) transverse d) none of the above CHOOSE THE CORRECT ANSWER

4. The relation between the velocity of light C, μ0 and ε 0 is given by the relation C = a) 1 / √μ 0 ε 0 b) √μ 0 ε 0 c) √μ 0 / ε 0 d) √ ε 0 / √μ 0 CHOOSE THE CORRECT ANSWER

5. Hertz produced electromagnetic waves of frequency a) 5 × 10 9 Hz b) 5 × 10 7 Hz c) 5 × Hz d) 5 × Hz CHOOSE THE CORRECT ANSWER

6. Electromagnetic waves cover a wide range of a) directions b) waves c) frequencies d) none of the above CHOOSE THE CORRECT ANSWER

7. Atoms and molecules in an electric discharge tube give rays. a) infra-red b) visible light c) UV d) X CHOOSE THE CORRECT ANSWER

8. The wavelength, the frequency and velocity of light are related by a) c = γ λ b) c = γ / λ c) c = λ / γ d) c = γ / λ 2 CHOOSE THE CORRECT ANSWER

9. The frequency range of AM band is a) 54 MHz to 890 MHz b) 88 MHz to 108 MHz c) 530 kHz to 1710 kHz d) 88 kHz to 108 kHz CHOOSE THE CORRECT ANSWER

10. The frequency range of FM band is from a) 54 MHz to 890 MHz b) 88 MHz to 108 MHz c) 530 kHz to 1710 kHz d) 88 kHz to 108 kHz CHOOSE THE CORRECT ANSWER

11. In Physiotherapy, lamps are used. a) infra-red b) ordinary c) UVray d) X ray CHOOSE THE CORRECT ANSWER

12. The wavelengths of the sodium emission lines are a) 5986 A o and 5890 A o b) 5896 A o and 5980 A o c) 5869 A o and 5890 A o d) 5896 A o and 5890 A o CHOOSE THE CORRECT ANSWER

13. The spectrum is used to identify the gas. a) continuous b) band c) line d) none of the above CHOOSE THE CORRECT ANSWER

14. Incandescent solids, carbon arc lamp etc. give spectrum. a) continuous b) band c) line d) none of the above CHOOSE THE CORRECT ANSWER

15. Using spectra, the molecular structure of the substance can be studied. a) continuous b) band c) line d) none of the above CHOOSE THE CORRECT ANSWER

16. The example of line absorption spectrum is spectrum. a) solar b) band c) line d) none of the above CHOOSE THE CORRECT ANSWER

17. The sun’s outer layer is called a) photosphere b) ionosphere c) thermosphere d) chromosphere. CHOOSE THE CORRECT ANSWER

18. The type of delayed fluorescence is called a) Raman effect b) Tyndal effect c) Rayleigh scattering d) phosphorescence CHOOSE THE CORRECT ANSWER

19. According to corpuscular theory, light energy is the kinetic energy of the a) waves b) light source c) photons d) corpuscles CHOOSE THE CORRECT ANSWER

20. Huygens assumed that light waves are in nature. a) longitudinal b) transverse c) mechanical d) stationary CHOOSE THE CORRECT ANSWER

21. The energy of each photon is given by the equation a) E = mc 2 b) E = h γ c) E = ma d) E = mv CHOOSE THE CORRECT ANSWER

22. The scattering of sunlight by the molecules of the earth’s atmosphere is called scattering. a) Raman b) Tyndal c) Rayleigh d) Einstein CHOOSE THE CORRECT ANSWER

23. The scattering of light by the colloidal particles is called effect. a) Raman b) Tyndal c) Rayleigh d) Einstein CHOOSE THE CORRECT ANSWER

24. In industry, spectroscopy is applied to study the properties of the materials. a) Raman b) Tyndal c) Rayleigh d) Einstein CHOOSE THE CORRECT ANSWER

25. The locus of the particles having the same state of vibration is called as a) wave b) corpuscle c) wavefront d) photon CHOOSE THE CORRECT ANSWER

26. A linear source of light will give rise to wavefront. a) spherical b) plane c) cylindrical d) elliptical CHOOSE THE CORRECT ANSWER

principle helps us to locate the position and the shape of the wavefront. a) Raman b) Tyndal c) Rayleigh d) Huygen CHOOSE THE CORRECT ANSWER

28. In reflection of light, the angle of incidence = the angle of a) refraction b) polarisation c) reflection d) diffraction CHOOSE THE CORRECT ANSWER

29. For total internal to take place, light must travel from denser medium to rarer medium. a) refraction b) polarisation c) reflection d) diffraction CHOOSE THE CORRECT ANSWER

30. The equation of bandwidth of interference fringes is β = a) λD / d b) λD d c) λ /D d d) λd / D CHOOSE THE CORRECT ANSWER

31. An important application of interference in thin films is the formation of rings. a) Raman’s b) Tyndal’s c) Rayleigh’s d) Newton’s CHOOSE THE CORRECT ANSWER

32. The radius of the nth dark ring equation is a) r n 2 = ( n R λ )2 b) r n = n 2 R λ c) r n = ( n R λ ) ½ d) r n = n R 2 λ CHOOSE THE CORRECT ANSWER

33. The amount of bending in diffraction depends on the a) size of the obstacle b) volume of the obstacle c) size of the obstacle d) wavelength of the incident wave. CHOOSE THE CORRECT ANSWER

34. In Fresnel diffraction, the incident wavefront is either a) spherical or ellipse b) plane or ellipsoid c) spherical or cylindrical d) elliptical CHOOSE THE CORRECT ANSWER

35. Using spectrometer, diffraction can be observed. a) Fraunhofer b) Raman c) Tyndal d) Rayleigh CHOOSE THE CORRECT ANSWER

36. The combined width of a slit and a ruling is called a) grating element b) prism element c) polaroid element d) element CHOOSE THE CORRECT ANSWER

37. In a plane diffraction grating, λ = a) nm / Sin θ b) Sin θ / nm c) nm / Sin θ d) ( nm Sin θ ) 1/2 CHOOSE THE CORRECT ANSWER

38. The phenomenon of proves that light waves are transverse. a) refraction b) polarisation c) reflection d) diffraction CHOOSE THE CORRECT ANSWER

39. The plane perpendicular to the plane of vibration is called plane of a) refraction b) polarisation c) reflection d) diffraction CHOOSE THE CORRECT ANSWER

40. A device that produces a plane light is called polariser. a) polarized b) reflected c) refracted d) diffracted CHOOSE THE CORRECT ANSWER

41. The angle of incidence at which the reflected beam is completely plane polarised is called angle of a) refraction b) diffraction c) reflection d) polarisation CHOOSE THE CORRECT ANSWER

42. The equation for Brewster’s law is μ = a) sin i p b) cot i p c) tan i p d) cos i p CHOOSE THE CORRECT ANSWER

43. The polarising angle for glass is a)  b)  c)  d)  CHOOSE THE CORRECT ANSWER

44. The pile of plates uses the polarisation by phenomenon. a) refraction b) polarisation c) reflection d) diffraction CHOOSE THE CORRECT ANSWER

45. The double refraction phenomenon was discovered by a) Bartholinus b) Malus c) Nicol d) Young CHOOSE THE CORRECT ANSWER

46. Crystals like mica, topaz etc. having two optic axes are called a) uni-axial crystals b) multi-axial crystals c) biaxial crystals d) none of the above CHOOSE THE CORRECT ANSWER

47. The refractive index for Canada balsam cement is for both the rays. a) b) c) d) CHOOSE THE CORRECT ANSWER

48. H polaroids use a thin film of a) herapathite crystals b) polyvinyl alcohol c) Canada balsam d) Na Cl CHOOSE THE CORRECT ANSWER

49. Polaroids are used as glasses. a) moon b) star c) planet d) sun CHOOSE THE CORRECT ANSWER

50. In an EM wave, the electric and the magnetic field vectors are at to each other and to the direction of propagation. a) 45  b) 90  c) 180  d) 145  CHOOSE THE CORRECT ANSWER

51. In an electromagnetic wave (a) power is equally transferred along the electric and magnetic fields (b) power is transmitted in a direction perpendicular to both the fields (c) power is transmitted along electric field (d) power is transmitted along magnetic field CHOOSE THE CORRECT ANSWER

52. Electromagnetic waves are (a) transverse (b) longitudinal (c) may be longitudinal or transverse (d) neither longitudinal nor transverse CHOOSE THE CORRECT ANSWER

53. Refractive index of glass is 1.5. Time taken for light to pass through a glass plate of thickness 10 cm is (a) 2 × 10 –8 s (b) 2 × 10 –10 s (c) 5 × 10 –8 s (d) 5 × 10 –10 s CHOOSE THE CORRECT ANSWER

54. In an electromagnetic wave the phase difference between electric field and magnetic field is (a) π/4 (b) π/2 (c) π (d) zero CHOOSE THE CORRECT ANSWER

55. Atomic spectrum should be (a) pure line spectrum (b) emission band spectrum (c) absorption line spectrum (d) absorption band spectrum. CHOOSE THE CORRECT ANSWER

56. When a drop of water is introduced between the glass plate and plano convex lens in Newton’s rings system, the ring system (a) contracts (b) expands (c) remains same (d) first expands, then contracts CHOOSE THE CORRECT ANSWER

57. A beam of monochromatic light enters from vacuum into a medium of refractive index μ. The ratio of the wavelengths of the incident and refracted waves is (a) μ : 1 (b) 1 : μ (c) μ2 : 1 (d) 1 : μ2 CHOOSE THE CORRECT ANSWER

58. If the wavelength of the light is reduced to one fourth, then the amount of scattering is (a) increased by 16 times (b) decreased by 16 times (c) increased by 256 times (d) decreased by 256 times CHOOSE THE CORRECT ANSWER

59. In Newton’s ring experiment the radii of the mth and (m + 4)th dark rings are respectively 5 mm and 7 mm. What is the value of m? (a) 2 (b) 4 (c) 8 (d) 10 CHOOSE THE CORRECT ANSWER

60. The path difference between two monochromatic light waves of wavelength 4000 Å is 2 × 10−7 m. The phase difference between them is (a) π (b) 2π (c) 3/2π(d) π/2 CHOOSE THE CORRECT ANSWER

61. In Young’s experiment, the third bright band for wavelength of light 6000 Å coincides with the fourth bright band for another source in the same arrangement. The wave length of the another source is (a) 4500 Å (b) 6000 Å (c) 5000 Å (d) 4000 Å CHOOSE THE CORRECT ANSWER

62. A light of wavelength 6000 Å is incident normally on a grating m wide with 2500 lines. Then the maximum order is (a) 3 (b) 2 (c) 1 (d) 4 CHOOSE THE CORRECT ANSWER

63. A diffraction pattern is obtained using a beam of red light. What happens if the red light is replaced by blue light? (a) bands disappear (b) no change (c) diffraction pattern becomes narrower and crowded together (d) diffraction pattern becomes broader and farther apart CHOOSE THE CORRECT ANSWER

64. The refractive index of the medium, for the polarising angle 60  is (a) (b) (c) 1.5 (d) CHOOSE THE CORRECT ANSWER

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