Question

A light ray I is incident on a plane mirror M. The mirror is rotated in the direction as shown in the figure by an arrow at a frequency 9 / π rev / sec. The light reflected by the mirror is received on the wall W at a distance 10 m from the axis of rotation. When the angle of incidence becomes 37^o, find the speed of the spot (a point) on the wall?

Answer 1

For a given incident ray, if the mirror is rotated through an angle θ , then the reflected ray turns through an angle of 2 θ . So if angular speed of mirror is ω then the angular speed by which the reflected ray is rotated is 2 ω.

When