A plano-convex lens fits exactly into a plano-concave lens. Their plane surfaces are parallel to each other. If the lenses are made of different material of refractive indices $μ_{1}$ and $μ_{2}$ and R is the radius of curvature of the curved surface of the lenses, then focal length of the combination is

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

$(\frac{R}{μ_{1} - μ_{2}})$

$(\frac{2 R}{μ_{2} - μ_{1}})$

$\frac{R}{2 (μ_{2} - μ_{1})}$

$\frac{R}{2 - (μ_{1} + μ_{2})}$

answer is A.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

From the lens maker formula for plano convex lens, $\frac{1}{f_{1}} = (μ_{1} - 1) (\frac{1}{R})$
For plano cancave lens $\frac{1}{f_{2}} = - (μ_{2} - 1) (\frac{1}{R})$
For the combination, $\frac{1}{f_{e q}} = \frac{1}{f_{1}} + \frac{1}{f_{2}} = (μ_{1} - μ_{2}) (\frac{1}{R})$
This gives us $f_{e q} = \frac{R}{μ_{1} - μ_{2}}$