Q. What will be the height of the image when an object of 2mm is placed at a distance 20 cm in front of the axis of a convex mirror of radius of curvature 40 cm?
A) 20 mm
B) 10 mm
C) 6 mm
D) 1 mm
Explanation
(d) $O = 2\ mm,\ u = \ - 20\ cm$
$f = \frac{R}{2} = \frac{40}{2} = 20\ cm$
From mirror formula,
$\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$
$\frac{1}{20} = \frac{1}{v} + \frac{1}{- 20}$
$\frac{1}{v} = \frac{1}{20} + \frac{1}{20}$
$\Rightarrow v\ = \ 10\ cm$
$\therefore\frac{I}{O} = \frac{v}{u}$
$\frac{I}{2} = \frac{10}{20}$
$\Rightarrow I\ \ = \ 1\ mm$
Height of image = 1 mm
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.