Optics Question 78
Question: A point source of light B is placed at a distance L in front of the centre of a 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 the image of the light source in the mirror is
[IIT-JEE (Screening) 2000]
Options:
A) d/2
B) d
C) 2d
D) 3d
Show Answer
Answer:
Correct Answer: D
Solution:
According to the following ray diagram $ HI=AB=d $
and $ DS=CD=\frac{d}{2} $
$ \because AH=2AD $
$ \Rightarrow GH=2CD=\frac{2d}{2}=d $
Similarly $ IJ=d $ so $ GJ=GH+HI+IJ $
$ =d+d+d=3d $
