Equivalent Lens Power | JEE Main 2025

JEE MAIN 2025

02-04-2025 SHIFT-2

Question

A bi-convex lens has radius of curvature of both the surfaces same as $1 / 6 \mathrm{~cm}$. If this lens is required to be replaced by another convex lens having different radii of curvatures on both sides $\left(R_{1} \neq R_{2}\right)$, without any change in lens power then possible combination of $R_{1}$ and $R_{2}$ is :

Select the correct option:

$\frac{1}{5} \mathrm{~cm}$ and $\frac{1}{7} \mathrm{~cm}$

$\frac{1}{3} \mathrm{~cm}$ and $\frac{1}{3} \mathrm{~cm}$

$\frac{1}{6} \mathrm{~cm}$ and $\frac{1}{9} \mathrm{~cm}$

$\frac{1}{3} \mathrm{~cm}$ and $\frac{1}{7} \mathrm{~cm}$

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

Solution

This will happen when $\frac{1}{f_{1}}=\frac{1}{f_{2}}$
$(\mu-1)\left(\frac{1}{R_{1}}-\frac{1}{-R_{2}}\right)=(\mu-1)\left(\frac{2}{R}\right)$
$\frac{1}{R_{1}}+\frac{1}{R_{2}}=\frac{2}{R}$

Question Tags

JEE Main

Physics

Medium

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