A point source of light S, placed at a
distance L in front of the centre of a mirror of width d,
hangs vertically on a wall. A man walks in front of the
mirror along a line parallel to th mirror at a distane
2L form it as shown.The greatest distance over which
he can see the image of the light source in the mirror is
(a) `d//2` (b) d (c) 2d (d) 3 d.

Explanation

The ray diagram will be as shown in Figure.
HI =AB=d, DS=CD=d/2
Since, AH=2AD,
` therefore GH = 2CD = 2 (d)/(2) = d `
Similarly IJ = d
GJ = GH+HI+IJ = d+d+d=3d