Q: The refractive index of a prism is 2. This prism can have what maximum refracting angle ?

Sol: Critical angle , $\large C = sin^{-1} (\frac{1}{\mu}) $

$\large C = sin^{-1} (\frac{1}{2}) = 30^o $

If A > 2 C , the ray does not emerge from the prism. So, maximum refracting angle can be 60° .