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MHT CET · Physics · Ray Optics

A concave lens (refractive index \(=1 \cdot 5\)) has both surfaces of same radius of curvature \(R\). If it is immersed in a liquid of refractive index \(1 \cdot 75\) it will act as a

  1. A concave lens of focal length (3.5) R
  2. B concave lens of focal length 2 R
  3. C convex lens of focal length (3.5) R
  4. D convex lens of focal length 2 R
Verified Solution

Answer & Solution

Correct Answer

(C) convex lens of focal length (3.5) R

Step-by-step Solution

Detailed explanation

\(\frac{1}{f} = \left(\frac{n_{lens}}{n_{medium}} - 1\right) \left(\frac{1}{R_1} - \frac{1}{R_2}\right)\) \(\frac{1}{f} = \left(\frac{1.5}{1.75} - 1\right) \left(\frac{1}{-R} - \frac{1}{R}\right)\)