Q. A spherical mirror forms an image of magnification 3. The object distance, if focal length of mirror is 24 cm, may be
A) 32 cm, 24 cm
B) 32 cm, 16 cm
C) 32 cm only
D) 16 cm only
Explanation
(b) $m = \frac{f}{f - u}$
If$\ m = + 3,\ $then
$3 = \frac{- 24}{- 24 - u}$
Or $- 24 - u = - 8\ $or$\ u + 24 = 8$
Or $\ u = 8 - 24\ cm = - 16\ cm$
If $\ m = - 3$, then
$- 3 = \frac{- 24}{- 24 - u}$
$u + 24 = - 8$
Or $\ u = - 32$cm
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.