Question

Two plane mirrors are inclined at $70^{\circ }$. A ray incident on one mirror at angle, $\theta$ after reflection falls on second mirror and is reflected from there parallel to first mirror. The value of $\theta$ is

• A. $45^{\circ }$
• B. $30^{\circ }$
• C. $55^{\circ }$
• D. $50^{\circ }$

Answer 1

Answer: (D)

Different angles as shown in the figure.
$\theta +40^{\circ }=90^{\circ }$
$\therefore \theta =90^{\circ }-40^{\circ }=50^{\circ }$