Question

The refractive index of a prism is $2$ . The prism can have a maximum refracting angle of

• A. $90^{\circ }$
• B. $60^{\circ }$
• C. $45^{\circ }$
• D. $30^{\circ }$

Answer 1

Answer: (B)

Critical angle ${\theta }_c={\sin }^{-1}\left(\frac{1}{\mu }\right)$
$={\sin }^{-1}\left(\frac{1}{2}\right)=30^{\circ }$
If $A>2{\theta }_e$, the ray does not emerge from the prism.
So, maximum angle can be $60^{\circ }$.