Question

A glass prism of refractive index 1.5 is immersed in water $(\mu =\frac{4}{3})$. A light beam incident normally on the face AB is totally reflected to reach the face BC if $sin\theta >\frac{8}{9}$

• A. True
• B. False

Answer 1

The correct option is A True

From figure it is clear that
Total internal reflection takes place at AC, only if $\theta >C$
$\Rightarrow sin\theta >sinC\Rightarrow sin\theta >\frac{1}{{}_{\omega }{\mu }_g}\Rightarrow sin\theta >\frac{1}{\frac{9}{8}}\Rightarrow sin\theta >\frac{8}{9}$