prac questions

$3.$ Wa rer ice has a refractive index of $1\mathrm{.}3.$

a$.$ alculate the critical angle for total internal

b$.$ Calculate, for $=40,$ the angle of refraction of lection of light travelling from ice to air. the light ray from side AD$.$

c$.$ Explain why the light ray will be totally internally The diagram shows the direction of a light ray entering reflected from side $AB.$ an ice cube from air. The light ray makes an angle $$

The angle $$ is now increased. with the normal to side AD of the cube.

d$.$ Determine, to the nearest degree, the minimum value of $$ required for the light ray to emerge into air from side $AB.$