Question

The angle between two mirror is ${60}^o$ and is kept fixed. A ray is incident on one mirror at an angle i as shown in figure. The angle i is slowly increased from $0^o$ to ${90}^o$. The net deviation suffered by the ray after two reflections is D. Which of the following plots for magnitude of ‘D’ vs ‘i’ is correct.

• A.
• B.
• C.
• D. None of these

Answer 1

The correct option is C

$D=\left(2i\right)+2(60-i)$
$2\times 60={120}^{\circ }$
Independent of i