Optics 1 Question 8
8. 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 $2 L$ from it as shown. The greatest distance over which he can see the image of the light source in the mirror is
$(2000,2 M)$
(a) $d / 2$
(b) $d$
(c) $2 d$
(d) $3 d$
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Answer:
Correct Answer: 8. (d)
Solution:
- The ray diagram will be as follows :
Since, $A H=2 A D$
$$ \therefore \quad G H=2 C D=2 \frac{d}{2}=d $$
Similarly,
$$ \begin{aligned} I J & =d \\ G J & =G H+H I+I J \\ & =d+d+d=3 d \end{aligned} $$
$$ \therefore \quad G J=G H+H I+I J $$
