Question

A ray of light incident normally on the first face of a prism of refracting angle $A$ and critical angle $C$. The ray emerges from the second face of the prism when the following condition satisfies :

• A. $C>A$
• B. $C$
• C. $C\ge A$
• D. $C\le A$

Answer 1

Answer: (C)

$C\ge A$

For ray to emerge out angle ${\gamma }^1\le C$-----------(1)
And in a prism $\gamma +{\gamma }^1=A$
and Here $\gamma =0,$ since light is incident normally on the first face.
so, $o+{\gamma }^1=A$
or ${\gamma }^1=A$
and From 1
$A\le C.$