If the focal length of objective lens is increased then

1. microscope will increase but that of telescope decrease.
2. microscope and telescope both will increase.
3. microscope and telescope both will decrease
4. microscope will decrease but that of telescope increase.

Magnifying power of microscope

=	LD	∝	1
	f_ef₀		f₀

Hence with increase f₀ magnifyig power of microscope decreases.

Magnifying power of telescope =	f₀	∝ f₀
	f_e

Hence with increase f₀ magnifying power of telescope increases.