Question

ABC represents the principal cross-section of an equilateral prism made with a transparent material. If PQRS indicates the path of a light ray, find the refractive index of the material.

• A. $\frac{1}{\sqrt{2}}$
• B. $\frac{2}{\sqrt{3}}$
• C. $\sqrt{2}$
• D. $\frac{\sqrt{3}}{2}$

Answer 1

The correct option is B $\frac{2}{\sqrt{3}}$


Given: Equilateral prism.
Solution : Since there is no bending of light at first interface, hence light is incident normally.
Now for second interface Snell's law
${\mu }_1\sin i={\mu }_2\sin r$
${\mu }_1\sin {60}^0=1\sin {90}^0$
${\mu }_1=\frac{1}{sin{60}^0}=\frac{2}{\sqrt{3}}$