MCQs (Multiple Choice Questions) Physical Optics 3

31 In photo-electric effect, the energy of ejected electrons depends on .

(a) The intensity of light                    (b) The frequency of light
(c) Both intensity and frequency (d) Wave length of the above

31. Longitudinal waves do not exhibit (show)

(a) Reflection                                     (b) Refraction

(c) Diffraction                                    (d) Polarisation

32. The locus of all points in a medium having the same phase of

vibration is called

(a) Crest                                              (b) Trough

(c) Wave length                                (d) Wave front

33. At a very large distance from a point source we get

(a) An elliptical wave front              (b) A cylindrical wave front

(c) A plane wave front                     (d) A rectangular wave front

34. Huygen’s principle states that

-           (a) Light travels in straight line

(b)       Light travels in electromagnetic waves

(c)        All points on primary wave front are source of secondary wavelets

(d)       Light has dual nature

35. In order to get the interference of light waves

(a)        The sources should be monochromatic

(b)       The sources should be phase coherent

(c)        The linear supper-position should be applicable

(d)       All of the above

36. In Young’s double slit experiment, the condition for constructive

interference (or bright fringes ) is

(a) d sin() (m + 1/2)A                        (b) d sin() = mA

(c) d sin0 = Off — I/2)A                   (d) 2d sine = rnA

37. In Young’s double slit experiment, the fringe spacing (or fringe

width) is equal to

(a) d sin() -= Era                                (b) d sint9 = mA/2

•           (c) d sin() = (m — 1/2).1             (d) d sin° = (m + 1/2)A

A. The velocity of light was determined accurately by

(a) Newton                                         (b) Michelson

(c) l-lygen                                           (d) Young

39. The condition for constructive interference of two coherent beams

is that the path difference should be

(a) Integral multiple of/1/2                 (b) Integral ryultiple of).

(c) Odd integral multiple of Al2 (d) Even integral multiple of).

40. The condition for destructive interference of two coherent waves is

that the oath difference should be

(a) Integral multiple of A/2         (b) Integral multiple of .A.

(c) Odd integral multiple of A/2 (d) Even integral multiple of Al2

31. d 32.






35. d 36.






39. b 40.


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