Question

Two mirrors are inclined at an angle $\theta$ as shown in the figure. Light ray is incident parallel to one of the mirrors. Light will start retracing its path after third reflection if:

• A. $\theta ={45}^o$
• B. $\theta ={30}^o$
• C. $\theta ={60}^o$
• D. $allthree$

Answer 1

The correct option is B $\theta ={30}^o$

In $△ABC°\theta +\theta +\theta +90°=180°\therefore \theta ={30}^o$