Question

An equilateral glass prism is made of a material of refractive index 1.500. Find its angle of minimum deviation.

Answer 1

When rays passes symmetrically ,then rays is going to through minimum
Minimum deviation $\delta =2i-A$

an equilateral prism so, A is prism angle $A={60}^o$

For minimum angle the angle of refraction should be half of prism angle.

So $r=A/2={30}^o$

now using the snell's law

$n_{air}sini=n_{glass}sinr$

$sini=1.5sin30$

$i=48.6$

Minimum deviation $\delta =2\times 48.6-60={37.2}^o$