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A ray of light is incident on a $60^\circ$ prism at the minimum deviation position. The angle of refraction at the first face (i.e., incident face) of the prism is
A
Zero
B
$30^\circ$
C
$45^\circ$
D
$60^\circ$
Detailed Solution
For a prism, $r_1 + r_2 = A$, where $r_1$ and $r_2$ are the angles of refraction at the two faces.
At minimum deviation the ray passes symmetrically through the prism: $r_1 = r_2 = r$
$2r = A$
$r = \frac{A}{2} = \frac{60^\circ}{2}$
$r = 30^\circ$
At minimum deviation the ray passes symmetrically through the prism: $r_1 = r_2 = r$
$2r = A$
$r = \frac{A}{2} = \frac{60^\circ}{2}$
$r = 30^\circ$