A monochromatic ray of light passes from air to glass. The wavelength of light in air is λ, the speed of light in air is c and in glass is V. If the refractive index of glass is 1.5, write down,

(a) the relationship between c and V,

(b) the wavelength of light in the glass.

(a) The relation between the speed of light in air c and in glass V is given by —

$μ = \dfrac{\text{Speed of light in vacuum or air (c) }}{\text {Speed of light in that medium (V)}} \\[0.5em] 1.5 = \dfrac{c}{V} \\[0.5em] \Rightarrow c = 1.5 V \\[0.5em]$

(b) Let wavelength of light in glass be λ₁ so we get,

$μ = \dfrac{λ}{λ$1} \\[0.5em] 1.5 = \dfrac{λ}{λ1} \\[0.5em] λ_1 = \dfrac{λ}{1.5} \\[0.5em]