Ray Optics and Optical Instruments - Result Question 3
3. 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) $50^{\circ}$
(b) $45^{\circ}$
(c) $30^{\circ}$
(d) $55^{\circ}$
[NEET Kar. 2013]
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Answer:
Correct Answer: 3. (a)
Solution:
- (a)
From fig. $40^{\circ}+\theta=90^{\circ} \therefore \theta=90^{\circ}-40^{\circ}=50^{\circ}$
