Q. For unit magnification, the distance of an object from a concave mirror of focal length $20\ cm$ will be
A) $20\ cm$
B) $10\ cm$
C) $40\ cm$
D) $60\ cm$
Explanation
(c) For $m = 1,\ u = 2f = 40\ cm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.