Question

Two adjacent walls and the ceiling of a rectangular room are mirror surfaced. The number of images of himself that an observer sees is:

A. 3 

B. 9 

C. 6 

D. 8

Answer 1

The number of images formed if two plane mirrors are kept at an angle \(\theta\) is given by, \(\frac{360^o}{\theta}\,if\,\frac{360^o}{\theta}\) is odd and it is given by \(\frac{360^o}{\theta}\,-1\,if\,\frac{360^o}{\theta}\) is even.

For \(\theta\) = 90^o  , number of images is \(\frac{360^o}{90^o}\,-1\,=\,4\,-\,1\,=3as\,\frac{360^o}{90^o}\,=\,4\)  is an even number.

So, 3 images will be formed for each perpendicular mirror pair. Thus, 6 images will be formed for adjacent walls and 3 fro wall and ceiling mirrors.