Question

A ray of light is incident at an angle of incidence i, on one face of a prism of angle A (assumed to be small) and emerges normally from the opposite face. If the refractive index of the prism is $\mu$, the angle of incidence i, is nearly equal to

• A. $A/\mu$
• B. $A/2\mu$
• C. $\mu A$
• D. $\frac{\mu A}{2}$

Answer 1

The correct option is C $\mu A$

$\alpha ={180}^0-{90}^0-A=90-A$

$r=90-\alpha =A$

from snell's law

${\mu }_{1}sini={\mu }_{2}sinr$

$1sini=\mu sinA$

for small angle

$i=\mu A$