Question:medium
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 materials of refractive indices \(\mu_1\) and \(\mu_2\) and \(R\) is the radius of curvature of the curved surfaces of the lenses, then the focal length of the combination is:
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 materials of refractive indices \(\mu_1\) and \(\mu_2\) and \(R\) is the radius of curvature of the curved surfaces of the lenses, then the focal length of the combination is:
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For lenses in contact:
\[
P_{\text{net}}=\sum P
\]
Sign convention is crucial.
Updated On: Mar 23, 2026
- \(\dfrac{R}{\mu_1-\mu_2}\)
- \(\dfrac{2R}{\mu_1-\mu_2}\)
- \(\dfrac{R}{2(\mu_1-\mu_2)}\)
- \(\dfrac{R}{2-(\mu_1+\mu_2)}\)
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The Correct Option is A
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