Q. A square wire of side 1 cm is placed perpendicular to the principle axis of a concave mirror of focal length 15 cm at a distance of 20 cm. The area enclosed by the image of the wire is
A) $4\ cm²$
B) $6\ cm²$
C) $2\ cm²$
D) $9\ cm²$
Explanation
(d) Given focal length of concave mirror
$f\ = \ - 15\ cm$
$u\ = \ - 20\ cm$
Magnification $m = \frac{f}{u\ - \ f}\ = \ \frac{- 15}{- 20\ + \ 15}$
$m\ = \ 3\ cm$
The area enclosed by the image of the wire
$\ = \ m²\ = \ 9\ cm²$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.