Optics – Wave Optics Quiz - ICSE Class 12 Physics
Free practice quiz: Optics – Wave Optics (ICSE Class 12 Physics). 40 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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In Young's double-slit experiment, if the distance between the slits is halved and the distance of the screen from the slits is doubled, how does the fringe width change?
- It remains the same
- It becomes half
- It becomes double
- It becomes four times
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Answer: D. It becomes four times
The fringe width (β) in Young's double-slit experiment is given by β = (λD)/d, where λ is the wavelength of light, D is the distance of the screen from the slits, and d is the distance between the slits. If d is halved (d' = d/2) and D is doubled (D' = 2D), the new fringe width β' = (λ(2D))/(d/2) = 4(λD)/d = 4β. Thus, the fringe width becomes four times.
The condition for the first minimum in a single-slit diffraction pattern is given by:
- a sin θ = λ
- a sin θ = 2λ
- a sin θ = 3λ/2
- a sin θ = 0
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Answer: A. a sin θ = λ
For a single slit of width 'a', the condition for minima is a sin θ = nλ, where n = ±1, ±2, ±3, ... For the first minimum (n=1), the condition is a sin θ = λ.
The polarization of light can be achieved by:
- Passing light through a Nicol prism
- Reflection from a surface
- Scattering of light
- All of the above
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Answer: D. All of the above
Light can be polarized through several methods. A Nicol prism is a device specifically designed to produce and analyze polarized light. Polarization also occurs upon reflection from dielectric surfaces (Brewster's law) and due to scattering of light by particles in the atmosphere (e.g., Rayleigh scattering).
Which property of light is demonstrated by the experiment of diffraction from a single slit?
- Particle nature
- Wave nature
- Quantum nature
- Dual nature
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Answer: B. Wave nature
Diffraction, the bending of light around obstacles or through narrow openings, is a characteristic behavior of waves. The interference patterns observed in diffraction experiments are direct evidence of the wave nature of light.
The phenomenon of interference of light is best observed when:
- The sources are monochromatic and coherent
- The sources are polychromatic and incoherent
- The sources are widely separated
- The screen is very close to the sources
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Answer: A. The sources are monochromatic and coherent
For clear and observable interference fringes, two conditions are crucial: 1. Monochromatic light (single wavelength) ensures that the fringe spacing is uniform. 2. Coherent sources ensure that the phase relationship between the waves is constant, leading to stable interference patterns. Wide separation of sources or a close screen would generally lead to less distinct or absent interference.