Question

Which one of the following statements is correct about the magnification of an optical microscope?

(a) Magnification increases with the increase in focal length of eyepiece.

(b) Magnification increases with the increase in focal length of objective.

(c) Magnification does not depend upon the focal length of eyepiece.

(d) Magnification decrease with the increase in focal length of eyepiece.

Answer 1

(d) Magnification decrease with the increase in focal length of eyepiece.

The magnification of compound microscope is given by the following formula m = \((-\frac{v_0}{u_0})(1+\frac{D}{f_e})\)

where, 

v₀ = image distance from objective lens, 

u₀ = object, distance from objective lens, 

f_e = focal length of eyepiece

D = least distance of distant vision. 

m ∝ 1/f_e

∴ Magnification will decrease with the increase in the focal length of the eyepiece.