Q. A convex lens of focal length 10 cm and image formed by it, is at least distance of distinct vision then the magnifying power is
A) 3.5
B) 2.5
C) 1.5
D) 1.4
Explanation
(a) The coverging lens used for magnification is called simple microscope or a magnifier.
When image is formed at $D$, the least distance of distinct vision, then magnifying power
$M = 1 + \frac{D}{f}$
Given, $D\ $= 25 cm, $f$ = 10 cm
$\therefore M = 1 + \frac{25}{10} = 1 + 2.5 = 3.5$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.