Image VelocityHardQuestion 20203
Question
An object moves toward a concave mirror with velocity v_obj. The velocity of the image is related by:
- Av_img = v_obj
- Bv_img = m² v_obj (where m is transverse magnification)Correct
- Cv_img = v_obj/m
- Dv_img = −v_obj
Correct answer
v_img = m² v_obj (where m is transverse magnification)
Explanation
From mirror formula, differentiating: dv/dt = (v²/u²)(du/dt) = m² × v_obj. For a real object moving toward a concave mirror at u = 2f (m = −1): image velocity equals object velocity. For m > 1, image moves faster.