Interference and Diffraction Multiple Choice Questions and Answers

51. In Newtons rings the central spot is

1. Always bright
2. always dark
3. can be bright or dark
4. of blue color

52. In plane transmission grating, the angle of diffraction for second order maxima for wavelength 5 x 10^-5 cm is 30 degree. Calculate the number of lines in one centimeter of the grating surface

1. 1000 lines/cm
2. 5000 lines/cm
3. 500 lines/cm
4. 10000 lines/cm

53. In reference with antireflection coating which of the following statement is true?

1. Thickness of the film should be changed for light of same wavelength but different intensity
2. Thickness of the film need not be changed for light of same wavelength but different intensity
3. Thickness of the film should be increased for light of same wavelength but higher intensity
4. Thickness of the film should be decreased for light of same wavelength but higher intensity

54. In reflected light the central fringes of Newtons ring is

1. dark
2. Bright
3. Uniform
4. Non uniform

55. In thin film of wedge shaped, by keeping all other parameters constant, if only wavelength of incident light is increased. What will be the effect on bandwidth?

1. Bandwidth increases
2. Bandwidth decreases
3. Bands will merge
4. There will not any effect

56. In wedge shaped film the interference pattern has nature

1. Parallel to the end where thickness is non-zero
2. Perpendicular to contact edge
3. Parallel to contact edge
4. Perpendicular to the end where thickness is non-zero

57. Interference in thin film is mainly because of

1. Division amplitude
2. Division of wave fronts
3. Addition of amplitude
4. Addition of wave fronts

58. Interference in thin film is mainly because of

1. Division amplitude
2. Division of wave fronts
3. Addition of amplitude
4. Addition of wave fronts

59. Interference of light is evidence that

1. The speed of light is very large
2. light is a transverse wave
3. light is electromagnetic in character
4. Light is a wave phenomenon

60. Interference pattern is observed in wedge-shaped film and bandwidth is noted. Now the angle of wedge is reduced to zero. What will be the effect on Bandwidth?

1. Bandwidth increases
2. Bandwidth decreases
3. Bands will disappear
4. There will not any effect