A fixed incident ray reflects from a rotating plane mirror. If the reflected ray turns through 70°, through how many degrees did the mirror rotate?
Physics · Geometrical optics · law of reflection and plane mirror
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Question

A fixed incident ray reflects from a rotating plane mirror. If the reflected ray turns through 70°, through how many degrees did the mirror rotate?

G1 Physics · Accepted Answer

The reflected ray rotates through twice the mirror angle. Therefore θ=70°/2=35°.