Question

A ray of laser light misses a target by about $3^{\circ }$ after reflecting off a polished surface as shown. If only the surface can be rotated, in what way it should be done for the light to hit the target?

($+$ indicates clockwise direction, and $-$ indicates anticlockwise direction)

• A. -1.5

Answer 1

The correct option is A -1.5
If we rotate the mirror by θ in anticlockwise direction, the reflected ray moves in anticlockwise direction by 2θ.

Since the target is $3^{\circ }$ in the anticlockwise direction from the reflected ray, if we rotate the polished surface by ${1.5}^{\circ }$ in the anticlockwise direction, the reflected would hit the target.

So, the answer is $-{1.5}^{\circ }$. ($-$ indicates anticlockwise direction)