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.

Options

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

Answer

a.

Explanation

`Delta`s IAB and ICD are similar.
`(CD)/(AB)=(IE)/(IF)=(3L)/(L)=3`
`CD=2AB=3d`