Question

To get three images of a single object, one should have two plane mirrors at an angle of

• A. $60^{°}$
• B. $90^{°}$
• C. $120^{°}$
• D. $30^{°}$

Answer 1

Answer: (B)

The number of images formed of two plane mirrors are placed at an angle $\theta$ is $n=\frac{360^{°}}{\theta }-1$
Here $n=3$
$\therefore 3=\frac{360^{°}}{\theta }-1$
$\Rightarrow \theta =\frac{360^{°}}{\theta }=90^{°}$