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JEE Main 2025 (2 Apr, Shift 2) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from JEE Main 2025 (2 Apr, Shift 2)

Q28JEE Main 2025 · 2 APR · SHIFT 2Medium

Spherical Surfaces & Thin Lenses

A bi-convex lens has radius of curvature of both the surfaces same as $1/6\text{ cm}$ . If this lens is required to be replaced by another convex lens having different radii of curvatures on both sides $(R_1 \neq R_2)$ , without any change in lens power then possible combination of $R_1$ and $R_2$ is:

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Answer: (b)

Same material, so power $\propto \frac{1}{R_1} + \frac{1}{R_2}$ .
Original: $6 + 6 = 12\ \text{cm}^{-1}$ .
(a) $3 + 7 = 10$ , (b) $5 + 7 = 12$ , (c) $R_1 = R_2$ not allowed, (d) $6 + 9 = 15$ .
So the answer is (b) $\frac{1}{5}$ cm and $\frac{1}{7}$ cm.

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