Question

A ray of light incident parallel to the base PQ of an isosceles right-angled triangular prism PQR suffers two successive total internal reflections at the faces PQ and QR before emerging reversed in direction as shown

If the refractive index of the material of the prism is $\mu$, then

• A. $\mu >\sqrt{5}$
• B. $\sqrt{3}<\mu <\sqrt{5}$
• C. $\sqrt{2}<\mu <\sqrt{5}$
• D. $\mu <\sqrt{2}$

Answer 1

The correct option is A

$\mu >\sqrt{5}$

45 + r > C

Also 45 - r > C

90 > C

$\mu >\sqrt{2}$