Optics Question 438

Question: Magnification of a compound microscope is 30. Focal length of eye-piece is 5 cm and the image is formed at a distance of distinct vision of 25 cm. The magnification of the objective lens is

[DPMT 2005]

Options:

A) 6

B) 5

C) 7.5

D) 10

Show Answer

Answer:

Correct Answer: B

Solution:

$ m=\frac{v _{o}}{u _{o}}( 1+\frac{D}{f _{e}} )=m _{o}( 1+\frac{D}{f _{e}} ) $

Therefore $ 30=m _{o}( 1+\frac{25}{5} )=m _{0}\times 6 $

Therefore $ m _{o}=5 $ .



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