A point source of light P is placed at a distance L in front of a mirror of width d hung vertically on a wall . A man walks infront of the mirror a long a line parallel to the mirror at a distance 2L as shown in the figure. The greatest distance over which he can see the image of the light source, in the mirror is

Options

A. d/2
B. d
C. 2d
D. 3d

Answer

D

Explanation

Given : Distance between the mirror and source of light = L , Width of mirror = d and distance between the mirror and man = 2L .
We know that as the distance between man mirror is twice the distance between the light source and mirror, therefore the greatest distance over which the man can see the image of light source = d + d + d = 3d .