(a) In an experiment to find the refractive index of glass, if yellow light is replaced by green light, then how will the refractive index of the glass change? Give a reason in support of your answer.
(b) What is the value of angle of deviation, when light ray falls normally on the surface during refraction?
(c) Is it possible to have a critical angle of water with respect to glass? (Write YES or NO)
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(a) The refractive index of the glass will increase.
Reason — The refractive index of a medium increases as the wavelength of light decreases. Green light has a shorter wavelength than yellow light, so the refractive index of glass for green light is greater than that for yellow light.
(b) The angle of deviation is 0° (zero), because a ray falling normally on the surface is incident along the normal, so it passes into the second medium undeviated.
(c) NO
Reason — A critical angle exists only when light travels from a denser medium to a rarer medium. Here the light would travel from water to glass, i.e., from a rarer medium to a denser medium, so total internal reflection is not possible and there is no critical angle.