Class 12 Physics Chapter 10 Wave Optics Solved Question Answers

1 Out of the following Statements which is not correct?

A When unpolarised light passes through Nicol’s prism, the emergent light is elliptically polarized

B Nicol’s prism works on the principle of double refraction and T.l.R.

C Nicol’s prism can be used both the produce and analyse polarized light

D Calcite and Quartz are both double refracting crystal

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Answer:When unpolarised light passes through Nicol’s prism, the emergent light is elliptically polarized

2 Which of the following is conserved when light waves interefere?

A phase

B intensity

C amplitude

D none of these

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Answer:none of these

3 Poisson’s bright spot was discovered by:

A Fresnel

B Rayleigh

C Poisson

D Fraunhoffer

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Answer:Poisson

4 When a polaroid is rotated, the intensity of light varies but never reduces to zero. It shows that the incident light is:

A unpolarised

B completely plane polarised

C partially plane polarised

D None of the above

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Answer:partially plane polarised

5 What is the reason for your answer to the above question?

A The two sources do not emit light of the same wavelength

B The two sources emit waves which travel with different speeds

C The two sources emit light waves of different amplitudes

D There is not constant phase difference between the waves emitted by the two sources

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Answer:There is not constant phase difference between the waves emitted by the two sources

6 The intensity of light emerging from the two slits, in Young’s experiment is in the ratio 1 : 4. The ratio of,the intensity of the minimum to that of the consecutive maximum will be:

A 1 : 4

B 1 : 9

C 1 : 16

D 2 : 3

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Answer:1 : 9

7 The theory of expanding universe is confirmed by the observation of the spectral lines of the star, which shows :

A green shift

B red shift

C violet shift

D yellow shift

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Answer:red shift

8 When a polaroid is rotated, the intensity of light does not vary. The incident light may be:

A unpolarised

B completely polarised

C partially plane polarised

D None of the above

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Answer:unpolarised

9 Two sources of light are said to be coherent when both give out light waves of the same:

A amplitude and phase

B intensity and wavelength

C speed

D wavelength and a constant phase difference

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Answer:wavelength and a constant phase difference

10 A single slit diffraction pattern is obtained using a beam of red light What happened the red light is replaced by the blue light?

A There is no change in diffraction pattern

B Diffraction fringes become narrower and crowded

C Diffraction fringes become broader and farther apart

D The diffraction pattern disappear

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Answer:Diffraction fringes become narrower and crowded

11 What happens to the interference pattern the two slits S1 and S2 in Young’s double experiment are illuminated by two independent but identical sources?

A The intensity of the bright fringes doubled

B The intensity of the bright fringes becomes four times

C Two sets of interference fringes overlap

D No interference pattern is observed

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Answer:No interference pattern is observed

12 For sustained interference, we need two sources which emit radiations :

A of the same intensity

B of the same amplitude

C having a constant phase difference

D None of these

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Answer:having a constant phase difference

13 The application of Doppler effect are:

A Doppler spectrometer

B Doppler radius

C Doppler velocimeter

D All of these

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Answer:All of these

14 The fringe width (β) of a diffraction pattern and the slit width d are related as: (c) β ∝ √d (d) β ∝ 1d2

A β ∝ d

B

C β ∝ √d

D

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Answer:B

15 In Young double slit experiment, a minimum is obtained when the phase difference of the superposing waves, is (n ∈ l):\

A nπ

B

C (2n + 1)π

D zero

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Answer:(2n + 1)π

16 What happens if one of the slits, say S₁ in Young’s double , slit experiment-is covered with a glass plate which absorbs half the intensity of light from it?

A The bright fringes become less-bright and the dark fringes have a finite light intensity

B The bright fringes become brighter and the dark fringes become darker

C The fringe width decreases

D No fringes will be observed

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