Question

A flat mirror $M$ is arranged parallel to the wall $W$ at a distance $l$ from it. The light produced by a point source $S$ kept on the wall is reflected by the mirror and produces a light spot on the wall. The mirror moves with velocity $v$ towards the wall.

• A. The spot of light will move with the speed $v$ on the wall
• B. The spot of light will move on the wall
• C. As the mirror comes closer the spot of light will become larger and shift away from the wall with speed larger than $v$
• D. The size of the light spot on the wall remains the same

Answer 1

Answer: (D)

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Since for refraction $\angle i=\angle r$ , so spot of light will not move on wall and will have same size of object