Question

If the reflected ray is rotated by an angle of $4\theta$ clockwise direction then the mirror was rotated by.

• A. $2\theta$ in anti-clockwise direction
• B. $4\theta$ in anti-clockwise direction
• C. $2\theta$ in clockwise direction
• D. $4\theta$ in clockwise direction

Answer 1

Answer: (A)

$2\theta$ in anti-clockwise direction

When a plane mirror is rotated through an angle θ, the reflected ray turns through the angle 2θ. But the size of the image remains unaffected only position changes.
Now given that the reflected ray is rotated by an angle of $4\theta$ in the clockwise direction
It means the mirror was rotated by $4\theta /2=2\theta$ in the clockwise direction.