Question

A ray of light is incident, from the ‘glass side’, at the glass–water interface, at an angle i. It emerges out parallel to the surface of water as shown in the Fig. The refractive index, μ_g , of glass, is

(1) (4/3) sin i

(2) 1/sin i

(3) 4/3

(4) 1

Answer 1

(2) 1/sin i

Let μ_g and μ_ω denote the refractive indices of glass and water, respectivly. Let rbe angle of refraction in wateμr, for ray incident in glass at angle i. From Snell’s law,

μ_g sin i = μ_ω sin r .....(1)

For refraction at water–air interface; using Snell’s law, we get