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MHT CET 2021 (21 Sep, Shift 2) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from MHT CET 2021 (21 Sep, Shift 2)

Q68MHT CET 2021 · 21 SEP · SHIFT 2Easy

Spherical Surfaces & Thin Lenses

A convex lens is dipped in a liquid whose refractive index is equal to refractive index of lens material. Then its focal length will

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Answer: (c)

$\frac{1}{f} = \left(\frac{\mu_l}{\mu_m} - 1\right)\left(\frac{1}{R_1} - \frac{1}{R_2}\right)$
If $\mu_m = \mu_l$ , the bracket is zero, so $\frac{1}{f} = 0$ and $f = \infty$ (no refraction at the surfaces).
So the answer is (c) become infinite.

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