Chapter 7.
WAVE OPTICS
1) When light travels from an optically rarer medium to an optically
denser medium, the
speed decreases because of change in:
a) Wavelength
b) Frequency
c) Amplitude
d) Phase
2) Light of wavelength 5000 A.U. falls on a plane reflecting surface. The
frequency of
reflected light is...
a) 6 x 1014Hz
b) 5 x 1014Hz
c) 2 x 1014Hz
d) 1.666 x 1014Hz
3) Light follows wave nature because...
a) Light rays travel in a straight line
b) Light exhibits the phenomenon of reflection and refraction
c) Light exhibits the phenomenon of interference
d) Light causes the phenomenon of photoelectric effect
4) Young’s double slit experiment is carried out using green, red and blue
light, one
colour at a time. The fringe widths recorded are WG, WR, and WB
respectively then...
a) WG > WB > WR
b) WB > WG > WR
c) WR > WB > WG
d) WR> WG > WB
5) The path difference between two waves meeting at a point is (11/4)λ.
The phase
difference between the two waves is...
a) 11 π/4
b) 11 π/2
c) 11 π
d) 22 π
6) Which of the following cannot produce two coherent sources?
a) Lloyd’s mirror
b) Fresnel biprism
c) Young’s double slit
d) Prism
7) The bending of beam of light around corners of obstacle is called...
a) Reflection
b) Diffraction
c) Refraction
d) Interference
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8) In a single slit diffraction pattern, first minima obtained with red light
of wavelength
6600 A.U. coincides with first maxima f some other wavelength λ then is...
a) 5500 A.U.
b) 5000 A.U.
c) 4800 A.U.
d) 4400 A.U.
9) State the essential condition for diffraction of light to occur.
a) The size of the aperture must be less when compared to the wavelength of light
b) The size of the aperture must be more when compared to the wavelength of light
c) The size of the aperture must be comparable to the wavelength of light
d) The size of the aperture should not be compared to the wavelength of light
10)What is the cause of diffraction?
a) Interference of primary wavelets
b) Interference of secondary wavelets
c) Reflection of primary wavelets
d) Reflection of secondary wavelets
11) What should be the order of the size of an obstacle or aperture for
diffraction light?
a) Order of wavelength of light
b) Order of wavelength of obstacle
c) Order in ranges of micrometer
d) Order in ranges of nanometer
12) A small circular disc is placed in the path of light from a distant
source. Identify the nature of the fringe produced.
a) Dual
b) Narrow
c) Dark
d) Bright
13) Single slit diffraction is completely immersed in water without
changing any other parameter. How is the width of the central maximum
affected?
a) Insignificant
b) Increases
c) Decreases
d) Becomes zero
14) What will be the linear width of the central maximum on a screen that
is kept 5 m away from the slit, if a light of wavelength 800 nm strikes a
slit of 5 mm width.
a) 1.2 mm
b) 5.6 mm
c) 6.5 mm
d) 9.7 mm
15) In young’s double-slit experiment, the width of the fringes obtained
when the light of wavelength 6000 È? is 2. 0 mm. What will be the fringe
width if the entire apparatus is immersed in a liquid of refractive index
1.33?
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a) 0.5 mm
b) 1.0 mm
c) 1.5 mm
d) 2.0 mm
16) A monochromatic light of wavelength 5100 È? from a narrow slit is
incident on a double slit. If the overall separation of 10 fringes on a screen
200 cm away is 2 cm then, the separation between the slit is
a) 1.10 mm
b) 0.51 mm
c) 0.22 mm
d) 0.11 mm
17) Consider interference between two waves from two sources of
intensities I and 4I. What is the ratio of intensities at the point where the
phase difference is π?
a) I
b) 9 I
c) 5 I
d) 9 I
18) The polarizing angle for a medium is 60o. The critical angle for this
medium is
a) sin-1 (0.321)
b) sin-1 (0.577)
c) sin-1 (0.732)
d) sin-1 (1)
19) Resolving power of telescope can be increased by increasing
(a) the wavelength
(b) the diameter of the objective
(c) the diameter of the eyepiece
(d) the focal length of the eyepiece
20) Polarization of light proves
(a) the corpuscular nature of light.
(b) quantum nature of light.
(c) transverse wave nature of light.
(d) longitudinal wave nature of light.
21) The wavefront due to a source situated at infinity is
(a) spherical
(b) cylindrical
(c) planar
(d) circular
22) A laser beam is coherent because it contains
(a) waves of several wavelengths.
(b) incoherent waves of a single wavelength.
(c) coherent waves of several wavelengths
(d) coherent waves of a single wavelength.
23) According to Huygens’ principle, light is a form of
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(a) particle
(b) rays
(c) wave
(d) radiation
24) Two coherent monochromatic light beams of intensities I and 41
superimpose. The maximum and minimum possible intensities in the
resulting beam are:
(a) 5I and I
(b) 5I and 3I
(c) 3I and I
(d) 9I and I
25) When exposed to sunlight, thin films of oil on water of the ten exhibit
brilliant colors due to the phenomenon of
(a) interference
(b) diffraction
(c) dispersion
(d) polarization
26) What happens if the monochromatic light used in Young’s double-slit
experiment is replaced by white light?
(a) No fringes are observed.
(b) All bright fringes become while.
(c) All bright fringes have colors between violet and red.
(d) Only the central fringe is white and all other fringes are colored.
27) When a compact disk is illuminated by a source of white light, colored
lines are observed. This is due to
(a) dispersion
(b) diffraction
(c) interference
(d) refraction
28) When an unpolarized light beam is an incident from the air onto glass
(n = 1.5) at the polarizing angle.
(a) The reflected beam is polarized completely
(b) Reflected and refracted beams are partially polarised
(c) Refracted beam is plane-polarized
(d) the Whole beam of light is refracted
29) Two periodic waves of intensities I1 and I2 pass through a region at the
same time in the same direction. The sum of maximum and minimum
intensities is:
(a) (I1 + I2)
(b) 2 (I1 + I2)
(c) (I1 + I2)
(d) 2 (I1 + I2)
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