Question

Obtain the equation for critical angle.

Answer 1

The angle of incidence in the denser medium for which the refracted ray grace the boundary is called the critical angle.

Snell’s law in Product form

n₁ sin i_c = n₂ sin 90°

n₁ sin i_c = n₂

sin i_c = `"n"_2/"n"_1`

here n₁ > n₂,

If the rarer medium is air

n₁ = n and n₂ = 1

sin i_c = `1/"n"`

i_c = sin^-1 `1/"n"`

Critical angle and total internal reflection