Physics - Geometrical Optics Question with Solution | TestHub

Let the angle between the mirrors be θ.

The ray is parallel to the second mirror, so it makes angle θ with the first mirror; after reflection it again makes angle θ with the first mirror.

For the final ray to emerge parallel to the first mirror, the ray between the two reflections must make angle θ with the second mirror.

The two mirrors and the middle ray form a triangle whose three angles are all θ:$3\theta =180^{\circ }\Rightarrow \theta =60^{\circ }$

Answer: 60