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JEE Main 2020 (6 Sep, Shift 2) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from JEE Main 2020 (6 Sep, Shift 2)

Q85JEE Main 2020 · 6 SEP · SHIFT 2Medium

Spherical Surfaces & Thin Lenses

A double convex lens has power P and same radii of curvature R of both the surfaces. The radius of curvature of a surface of a plano-convex lens made of the same material with power 1.5 P is:

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Answer: (a)

Double convex: $P = (\mu - 1)\frac{2}{R}$ .
Plano-convex: $1.5P = (\mu - 1)\frac{1}{R'} \Rightarrow (\mu - 1)\frac{1}{R'} = (\mu - 1)\frac{3}{R}$
So the answer is (a) $R' = \frac{R}{3}$ .

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