# MCQ Questions for Class 12 Physics Chapter 10 Wave Optics with Answer

MCQ Questions for Class 12 Physics Chapter 10 Download Free PDF: CBSE RBSE and NCERT Physics class 12 MCQs for Chapter 10 “Wave Optics” is very important for the students who want to get good marks. Neet MCQs

Page Contents

MCQ Questions for Class 12 Physics Chapter 10 Download Free PDF: CBSE RBSE and NCERT Physics class 12 MCQs for Chapter 10 “Wave Optics” is very important for the students who want to get good marks. Neet MCQs

## MCQ Questions for Class 12 Physics Chapter 10 Wave Optics with PDF

Q.1. The locus of all particles in a medium, vibrating in the same phase is called
(a) wavelet
(b) fringe
(c) wave front
(d) None of these

Q.2. Which of the following is correct for light diverging from a point source?
(a) The intensity decreases in proportion for the distance squared.
(b) The wavefront is parabolic.
(c) The intensity at the wavelingth does depend of the distance.
(d) None of these.

Q.3. Wavefront is the locus of all points, where the particles of the medium vibrate with the same
(a) phase
(b) amplitude
(c) frequency
(d) period

Q.4. The phenomena which is not explained by Huygen’s construction of wavefront
(a) reflection
(b) diffraction
(c) refraction
(d) origin of spectra

Q.5. Huygen’s concept of secondary wave
(a) allows us to find the focal length of a thick lens
(b) is a geometrical method to find a wavefront
(c) is used to determine the velocity of light
(d) is used to explain polarisation

Q.6. A plane wave passes through a convex lens. The geometrical shape of the wavefront that emerges is
(a) plane
(b) diverging spherical
(c) converging spherical
(d) None of these

Q.7. Spherical wavefronts, emanating from a point source, strike a plane reflecting surface. What will happen to these wave fronts, immediately after reflection?
(a) They will remain spherical with the same curvature, both in magnitude and sign.
(b) They will become plane wave fronts.
(c) They will remain spherical, with the same curvature, but sign of curvature reversed.
(d) They will remain spherical, but with different curvature, both in magnitude and sign.

Q.8. When light suffers reflection at the interface between water and glass, the change of phase in the reflected wave is
(a) zero
(b) π
(c) π/2
(d) 2π

Q.9. Two plane wavefronts of light, one incident on a thin convex lens and another on the refracting face of a thin prism. After refraction at them, the emerging wavefronts respectively become
(a) plane wavefront and plane wavefront
(b) plane wavefront and spherical wavefront
(c) spherical wavefront and plane wavefront
(d) spherical wavefront and spherical wavefront
(e) elliptical wavefront and spherical wavefront

Q.10. When a film is illuminated by white light, its upper portion appears dark. Path difference between two reflected beams at the spot must be
(a) zero
(b) λ/2
(c) 2 λ/2
(d) π

Q.11. If two coherent sources are vibrating in phase then we have constructive interference at any point P whenever the path difference is

(a) (n+1/2)λ
(b) nλ/2
(c) (n-1/2)λ
(d) nλ

Q.12. If two sources are coherent, then the phase difference (􀁉) between the waves produced by them at any point
(a) will change with time and we will have stable positions of maxima and minima.
(b) will not change with time and we have unstable positions of maxima and minima.
(c) Positions of will not change with time and we will have stable positions of maxima and minima.
(d) will change with time and we will have unstable positions of maxima and minima.

Q.13. The device which produces highly coherent sources is
(a) Fresnel biprism
(b) Young’s double slit
(c) Laser
(d) Lloyd’s mirror

Q.14. Which of the following, cannot produce two coherent sources?
(a) Lloyd’s mirror
(b) Fresnel biprism
(c) Young’s double slit
(d) Prism

Q.15. Coherence is a measure of
(a) capability of producing interference by wave
(b) waves being diffracted
(c) waves being reflected
(d) waves being refracted

Q.16. Two sources of light are said to be coherent, when they give light waves of same
(a) amplitude and phase
(b) wavelength and constant phase difference
(c) intensity and wavelength
(d) phase and speed

Q.17. Intensity of light depends on
(a) amplitude
(b) frequency
(c) wavelength
(d) velocity

Q.18. The colour of bright fringe nearest to central achromatic
fringe in the interference pattern with white light will be
(a) violet
(b) red
(c) green
(d) yellow

Q.19. The correct formula for fringe visibility is
(a) V=(Imax-Imin)/(Imax+Imin)
(b) V=(Imax+Imin)/(Imax-Imin)
(c) V=Imax/Imin
(d) V=Imin/Imax

Q.20. Laser light is considered to be coherent because it consists of
(a) many wavelengths
(b) uncoordinated wavelengths
(c) coordinated waves of exactly the same wavelength
(d) divergent beam

Q.21. The interfering fringes formed by a thin oil film on water are seen in yellow light of sodium lamp. We find the fringes
(a) coloured
(b) black and white
(c) yellow and black
(d) coloured without yellow

Q.22. In Young’s Double slit experiment, if the distance
between the slit and screen (D) is comparable with fringe
width (B), the fringe pattern on screen will
(a) strictly be a parabola
(b) strictly be a hyperbola
(c) be a elliptical
(d) be a straight line

Q.23. If Young’s double slit experiment is performed in water
keeping the rest of the set-up same, the fringes will
(a) increase in width
(b) decrease in width
(c) remain unchanged
(d) not be formed

Q.24. In the Young’s Double slit experiment, when we place a converging lens after the slits and place the screen at the focus of the lens, it
(a) introduces an extra path difference in the parallel beam.
(b) introduces no path difference in the parallel beam.
(c) introduces an extra phase difference in the parallel beam.
(d) introduces an extra fringe in the diffraction pattern.

Q.25. The fringe width for red colours as compared to that for violet colour is approximately
(a) 3 times
(b) 2 times
(c) 4 times
(d) 8 times

Q.26. In Young’s double slit experiment, the minimum amplitude is obtained when the phase difference of super-imposing waves is (where n = 1, 2, 3, …)
(a) zero
(b) (2 n – 1) π
(c) n π
(d) (n + 1) π

Q.27. The fringe width in a Young’s double slit experiment can
be increased if we decrease
(a) width of slits
(b) separation of slits
(c) wavelength of light used
(d) distance between slits and screen

Q.28. In Young’s double slit experiment, one slit is covered with
red filter and another slit is covered by green filter, then
interference pattern will be
(a) red
(b) green
(c) yellow
(d) invisible

Q.29. Instead of using two slits, if we use two separate identical sodium lamps in Young’s experiment, which of the following will occur?
(a) General illumination
(b) Widely separate interference
(c) Very bright maxima
(d) Very dark minima

Q.30. Which of the following is not essential for two sources of light in Young’s double slit experiment to produce a sustained interference?
(a) Equal wavelength
(b) Equal intensity
(c) Constant phase relationship
(d) Equal frequency

Q.31. In Young’s double slit experiment, the locus of the point P lying in a plane with a constant path difference between the two interfering waves is
(a) a hyperbola
(b) a straight line
(c) an ellipse
(d) a parabola

Q.32. If the width of the slit in single slit diffraction experiment is doubled, then the central maximum of diffraction pattern becomes
(a) broader and brighter
(b) sharper and brighter
(c) sharper and fainter

Q.33. A diffraction pattern is obtained by using beam of red. light what will happen, if red light is replaced by the blue light?
(a) Bands disappear.
(b) Bands become broader and farther apart.
(c) No change will take place.
(d) Diffraction bands become narrow and crowded together.

Q.34. When monochromatic light is replaced by white light in Fresnel’s biprism arrangement, the central fringe is
(a) coloured
(b) white
(c) dark
(d) None of these

Answer: (b) At the centre, all colours meet in phase, hence central fringe is white.

Q.35. The condition for observing Fraunhoffer diffraction from a single slit is that the light wavefront incident on the slit should be
(a) spherical
(b) cylindrical
(c) plane
(d) elliptical

Q.36. The phenomenon of diffraction can be treated as interference phenomenon if the number of coherent sources is
(a) one
(b) two
(c) zero
(d) infinity

Q.37. The diffraction effects in a microscopic specimen become important when the separation between two points is
(a) much greater than the wavelength of light used.
(b) much less than the wavelength of light used.
(c) comparable to the wavelength of light used.
(d) independent of the wavelength of light used.

Q.38. What is the Brewester’s angle for air to glass transition?( μag = 1.5)
(a) tan (1.5)
(b) sin (1.5)
(c) sin–1 (1.5)
(d) tan–1 (1.5)

Q.39. When ordinary light is made incident on a quarter wave plate, the emergent light is
(a) linearly polarised
(b) circulary polarised
(c) unpolarised
(d) elliptically polarised

Q.40. Transverse nature of light was confirmed by the phenomenon of
(a) refreaction of light
(b) diffraction of light
(c) dispersion of light
(d) polarization of light

Q.41. In the case of linearly polarized light, the magnitude of the electric field vector
(a) is parallel to the direction of propagation
(b) does not changes with time
(c) increases linearly with time
(d) varies periodically with time

Q.42. Unpolarized light is incident on a plane glass surface The angle of incidence so that reflected and refracted rays are perpendicular to each other, them
(a) tan iβ = μ/2
(b) tan iβ = μ
(c) sin iβ = μ
(d) cos iβ = μ

Q.43. Light waves can be polarised because they
(a) have high frequencies
(b) have short wavelength
(c) are transverse
(d) can be reflected

Q.44. Light transmitted by nicol prism is
(a) unpolarised
(b) plane polarised
(c) circularly polarised
(d) elliptically polarised

Q.45. Optically active substances are those substances which
(a) produces polarised light
(b) produces double refraction
(c) rotate the plane of polarisation of polarised light
(d) converts a plane polarised light into circularly polarised light.

Q.46. Polaroid glass is used in sun glasses because
(a) it reduces the light intensity to half on account of polarisation
(b) it is fashionable
(c) it has good colour
(d) it is cheaper.

Q.47. In the propagation of light waves, the angle between the plane of vibration and plane of polarisaiton is
(a) 0º
(b) 90º
(c) 45º
(d) 80º

Q.48. In the propagation of electromagnetic waves, the angle between the direction of propagation and plane of polarisation is
(a) 0º
(b) 45º
(c) 90º
(d) 180º

Q.49. When unpolarised light is incident on a plane glass plate at Brewster’s angle, then which of the following statements is correct?
(a) Reflected and refracted rays are completely polarised with their planes of polarization parallel to each other
(b) Reflected and refracted rays are completely polarised with their planes of polarization perpendicular to each other
(c) Reflected light is plane polarised but transmitted light is partially polarised
(d) Reflected light is partially polarised but refracted light is plane polarised