Q. The radius of curvature of concave mirror is 24 cm and the image is magnified by 1.5 times. The object distance is
A) 20 cm
B) 8 cm
C) 16 cm
D) 24 cm
Explanation
(a) Given that, $R = \ - 24\ cm$
$f = \ - 12\ cm\ and\ m = 1.5$
By the lens formula,
$\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$
$\frac{1}{1.5u} + \frac{1}{u} = \ - \frac{1}{12}$
$\frac{2.5}{1.5u} = \ - \frac{1}{12}$
Or$u = \ - 20\ cm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.