Question

A beam of light enters a flat pane of glass with parallel and smooth surfaces at an angle of incidence of 300. the refractive index of the glass is 1.2. the light is refracted when it enters the glass plate and refracted again when it leaves. what is the exiting angle of refraction? answer in degrees but do not enter the unit.

Answer 1

Angle of refraction is calculated by Snell's law

it is given as

$n_1sin i = n_2 sinr$

now for the first surface we can say

$1* sin30 = 1.2 * sinr$

$r = 24.6 degree$

now this is the angle of incidence on the next surface

so we will again apply snell's law

$n_1sin i = n_2 sinr$

$1.2* sin24.6 = 1 * sinr$

$r = 30 degree$

so the final angle of refraction after two refraction will be same as that of angle of incidence.

So its 30 degree.