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

Question

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

Toppr Admin · Accepted Answer