A concave mirror moves at 3 cm/s. At an instant the image must be stationary in the laboratory frame. Find the required magnitude of image velocity relative to the mirror in cm/s.
Physics · Geometrical optics · spherical mirror
JEE Mains NEET

Question

A concave mirror moves at 3 cm/s. At an instant the image must be stationary in the laboratory frame. Find the required magnitude of image velocity relative to the mirror in cm/s.

G1 Physics · Accepted Answer

Laboratory image velocity is Vₘ+Vᵢ(rel). For zero result, Vᵢ(rel)=−Vₘ, so the required magnitude is 3 cm/s.