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)

50$^{\circ}$

Answer 2

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