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Question: Answered & Verified by Expert
A convex lens is dipped in a liquid whose refractive index is equal to refractive index of lens material. Then its focal length will
PhysicsRay OpticsMHT CETMHT CET 2021 (21 Sep Shift 2)
Options:
  • A increase
  • B remain unchanged
  • C become infinite
  • D become zero
Solution:
1973 Upvotes Verified Answer
The correct answer is: become infinite
For a lens $\frac{1}{\mathrm{f}}=\left(\mu^{\prime}-1\right)\left(\frac{1}{\mathrm{R}_1}-\frac{1}{\mathrm{R}_2}\right)$
Where $\mu^{\prime}=\frac{\mu_{\mathrm{g}}}{\mu_{\ell}}=1$
$$
\therefore \frac{1}{\mathrm{f}}=0 \text { or } \mathrm{f}=\infty
$$

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