Question

A compound microscope having $f_0$= 7mm, $f_e$= 20 mm and distance between the lenses is 20 cm. If image is formed at least distance of distinct vision then magnifying power ?

• A. 388
• B. 400
• C. 220
• D. 120

Answer 1

The correct option is A 388

In case image is formed at infinity, the magnification provided by the

compounds microscope is,

$M=\frac{L}{fo}(1+\frac{D}{fe})$

L = Length of tube = 20 cm.

D = Distance of near vision = 25 cm

so, $M=\frac{20}{0.7}(1+\frac{25}{2})\simeq 385.7$