R4RIN – MCQs, Mock Tests | NCERT Class 12 MCQ Questions for Class 12 Physics Chapter 10 Wave Optics

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?

1. The bright fringes become less-bright and the dark fringes have a finite light intensity
2. The bright fringes become brighter and the dark fringes become darker
3. The fringe width decreases
4. No fringes will be observed

✅ Correct Answer: 1

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?

1. The intensity of the bright fringes doubled
2. The intensity of the bright fringes becomes four times
3. Two sets of interference fringes overlap
4. No interference pattern is observed

✅ Correct Answer: 4

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

1. The two sources do not emit light of the same wavelength
2. The two sources emit waves which travel with different speeds
3. The two sources emit light waves of different amplitudes
4. There is not constant phase difference between the waves emitted by the two sources

✅ Correct Answer: 4

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

1. There is no change in diffraction pattern
2. Diffraction fringes become narrower and crowded
3. Diffraction fringes become broader and farther apart
4. The diffraction pattern disappear

✅ Correct Answer: 2

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

1. unpolarised
2. completely plane polarised
3. partially plane polarised
4. None of the above

✅ Correct Answer: 3

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

1. unpolarised
2. completely polarised
3. partially plane polarised
4. None of the above

✅ Correct Answer: 1

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

1. of the same intensity
2. of the same amplitude
3. having a constant phase difference
4. None of the above

✅ Correct Answer: 3

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

1. amplitude and phase
2. intensity and wavelength
3. speed
4. wavelength and a constant phase difference

✅ Correct Answer: 4

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:

1. 1 : 4
2. 1 : 9
3. 1 : 16
4. 2 : 3

✅ Correct Answer: 2

Poisson’s bright spot was discovered by:

1. Fresnel
2. Rayleigh
3. Poisson
4. Fraunhoffer

✅ Correct Answer: 3

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

1. green shift
2. red shift
3. violet shift
4. yellow shift

✅ Correct Answer: 2

The application of Doppler effect are:

1. Doppler spectrometer
2. Doppler radius
3. Doppler velocimeter
4. All the above

✅ Correct Answer: 4

Which of the following is conserved when light waves interefere?

1. phase
2. intensity
3. amplitude
4. None of the above

✅ Correct Answer: 4

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

1. nπ
2. (n + 12)π
3. (2n + 1)π
4. zero

✅ Correct Answer: 3

The angle of minimum deviation of a prism depends upon the aggie of:

1. incidence
2. reflection
3. prism
4. None of the above

✅ Correct Answer: 3

he minimum value of the refractive index is:

1. zero
2. 1
3. less than 1 but not zero
4. more than 1

✅ Correct Answer: 3

Polarization of light prove the :

1. corpuscular nature of light
2. quantum nature of light
3. Transverse wave nature of light
4. Longitudinal wave nature of light

✅ Correct Answer: 3

Out of the following Statements which is not correct?

1. When unpolarised light passes through Nicol’s prism, the emergent light is elliptically polarized
2. Nicol’s prism works on the principle of double refraction and T.l.R.
3. Nicol’s prism can be used both the produce and analyse polarized light
4. Calcite and Quartz are both double refracting crystal

✅ Correct Answer: 1

Polaroid glasses is used in sun glasses because :

1. It reduces the light intensity to half on account of polarization
2. It is fashionable
3. It has good colour
4. It is cheaper

✅ Correct Answer: 1

In vacuum, the speed of light depends upon :

1. frequency
2. velocity
3. wave length
4. None of the these

✅ Correct Answer: 4

The fringe width (β) of a diffraction pattern and the slit width d are related as:

1. β ∝ d
2. β ∝1d
3. β ∝ √d
4. β ∝ 1d2

✅ Correct Answer: 2

C.V. Raman was awarded the Nobel prize for his work associated with which of the following phenomenon of radiations?

1. scattering
2. diffraction
3. interference
4. polarisation

✅ Correct Answer: 1

Light takes 10-10 to cross a glass slab. What is the thickness of the glass slab?

1. 2 CM
2. 3 CM
3. 2.5 CM
4. 3.5 CM

✅ Correct Answer: 2

In Young’s double slit experiment, the central point on the screen is:

1. bright
2. dark
3. first bright and later dark
4. first dark and later bright

✅ Correct Answer: 1

In Young’s double slit experiment the distance between the slit and the screen is doubled and the separation between the slit is reduced to half. The fringe width:

1. is doubled
2. become four time
3. is halfed
4. remain unchanged

✅ Correct Answer: 2

In a Young’s double slit experiment the distance between the slit is 1 mm and the distance of screen from the slit is 1 m. If light of wavelength 6000 A is used then the fringe width is:

1. 0.4 mm
2. 0.5 mm
3. 0.6 mm
4. 0.8 mm

✅ Correct Answer: 3

A person cannot see object clearly beyond 50 cm. The pow er of the lens to correct his vision is :

1. +0.5 dioptre
2. -0.5 dioptre
3. -2 dioptre
4. +2 dioptre

✅ Correct Answer: 3

A phase difference of 5π corresponds to a path difference (in terms of λ) of:

1. 5λ
2. 10λ
3. 5λ/2
4. 2λ

✅ Correct Answer: 3

A polaroid produces a strong beam of light which is :

1. circularly polarised
2. elliptically polarised
3. plane polarised
4. unpolarised

✅ Correct Answer: 2

Images of a distant lamp seen through a fire cloth rotate on rotating the cloth. This is due to the phenomenon of:

1. interference
2. diffraction
3. polarisation
4. scattering

✅ Correct Answer: 2

A young’s double slit experiment uses a monochromatic source. The shape of interference fringes formed on a screen is :

1. parabola
2. straight line
3. circle
4. hyperbola

✅ Correct Answer: 2

A monochromatic light is refracted from air into a glass of refractive index µ. The ratio of the wavelengths of the incident and the refracted waves is:

1. 1 : µ
2. 1 : µ²
3. µ : 1
4. µ² : 1

✅ Correct Answer: 3

The focal length of the lens is 50 cm; then its power is:

1. +2D
2. +1D
3. -2D
4. -1D

✅ Correct Answer: 1

In the above question, the number of the lens is:

1. +2
2. +1
3. -2
4. -1

✅ Correct Answer: 1

The refractive index of diamond is about:

1. 1
2. 1.42
3. 2.42
4. 4.24

✅ Correct Answer: 2

Two lenses having power +6 D and -4 D are placed in contact. The power of the combination is

1. -2D
2. -4D
3. +4D
4. +2 D

✅ Correct Answer: 4

Diffraction was discovered by :

1. Grimaldi
2. Thomas Young
3. Malus
4. Huygens

✅ Correct Answer: 1

The electromagnetic wave theory of light fails to explain :

1. compton effect
2. photoelectric effect
3. neither (a) nor (b)
4. Both (a) and (b)

✅ Correct Answer: 1