Question

A light ray travels at some angle (not head-on) from water in a rectangular aquarium, through the glass side, and out into the air. The indices of refraction for water, glass, and air are 1.33, about 1.6, and 1.0, respectively.
Rank the materials in descending order according to the angles of refraction made by the light ray with the normal in each.

• A. air, water, glass.
• B. air, glass, water.
• C. water, air, glass.
• D. water, glass, air
• E. glass, water, air

Answer 1

The correct option is A air, water, glass.

From snell's law, for light travelling from one medium to another, $\mu sinr=constant$

where $r$ is the angle of refraction that the light makes with the normal in the medium,

$⟹sinr\propto \frac{1}{\mu }$

Since ${\mu }_{glass}>{\mu }_{water}>{\mu }_{air}$,

$r_{air}>r_{water}>r_{glass}$