Question

A point source of light B is placed at a distance $L$ in front of the centre of the mirror of width $d$ hung 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 he image of the light source in the mirror is:

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

Answer 1

The correct option is D $3d$

$\begin{array}{c}\frac{M_1{M}_2}{I{M}_2}=\frac{L_{2}O}{10}\\ \frac{\frac{d}{2}}{L}=\frac{L_{2}O}{3L}\\ L_{2}D=\frac{3d}{2}\\ \text{Similarly}O{L}_1=\frac{3d}{2}\\ L_1{L}_2=\frac{3d}{2}+\frac{3d}{2}=3d\\ \text{So option}D\text{is correct}\end{array}$