If the focal length of the objective lens is increased then

Options

A. microscope will increase but that of telescope decrease
B. microscope and telescope, both will increase
C. microscope and telescope, both will decrease
D. microscope will decrease, but that of telescope will increase.

Answer

D

Explanation

For microscope, `M = (v_(0))/(-u_(0))(1 + (d)/(f_(e)))`
and for telescope, `M = (f_(0))/(f_(e))(1 + (f_(e))/(d))`
When we increase `f_(e)` : `M` for microscope decreases and `M` for telescope increases.