Consider the figure of equilateral prism.
According to Snell's law for incident ray is.
=√2 Substitute the value in above expression we get.
=√2 sin‌r1=0 r1=0 According to Snell's law for emitted ray is.
= sin‌e=√2‌sin‌r2 The angles of an equilateral triangle is
60°.
sin‌e=√2‌sin‌60° sin‌e=√2×>1 Thus, the light is incidenting is more than critical angle and total internally reflected.
The angle of deviation is given as,
δd=(i+e)−(r1+r2) Substitute the valuc in above expression.
δd=0−60°=−60° |δd|=60°