Question

Two thin lenses of focal lengths f₁ and f₂ are in contact and coaxial. Its power is same as power of a single lens given by
(a) $\frac{f_{1}+f_{2}}{f_{1}f_{2}}$(b) $\sqrt{\bigg \lgroup \frac{f_{1}}{f_{2}}\bigg \rgroup}$(c) $\sqrt{\bigg \lgroup \frac{f_{2}}{f_{1}}\bigg \rgroup}$(d) $\frac{f_{1}+f_{2}}{2}$

Answer 1

$<b>$

Option D is correct

Answer 2

Heya mate!!

Option (A) is correct.