Question

If the focal length of objective and eye lens are `1.2 cm` and `3 cm` respectively and the object is put `1.25cm` away from the objective lens and the final image is formed at infinity. The magnifying power of the microscope is
A. 150
B. 200
C. 250
D. 400

Answer 1

Correct Answer - B
(b) When final image is formed at infinity, then magnifying power
`M_(oo)=v_(0)/u_(0)xxD/(f_(e))`
From, `1/(f_(o))=1/v_(o)-1/u_(o)`
`1/(+1.2)=1/v_(o)-1/((-1.25))`
`rArr v_(o)=30 cm`
`abs(M_(oo))=30/1.25xx25/3=200`