# A point source of light S, placed at a distance L in front of the centre of a plane mirror of width d, hangs vertically on a wall…

Q: A point source of light S, placed at a distance L in front of the centre of a plane mirror of width d, hangs vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance 2L from 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) 2 d

(D) 3 d

Ans: (d)

Sol:

As triangle ΔS’AB & ΔS’PQ are similar

$\large \frac{d}{PQ} = \frac{L}{3L}$

PQ = 3 d

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