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MHT CET · Physics · Ray Optics

A convex lens of refractive index 1.5 has power 3D. It is placed in a liquid of refractive index 2 . The new power of the lens is

  1. A \(3D\)
  2. B \(0 \cdot 75 \mathrm{D}\)
  3. C \(1 \cdot 5 \mathrm{D}\)
  4. D \(2D\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(1 \cdot 5 \mathrm{D}\)

Step-by-step Solution

Detailed explanation

\( P_l = P_a \frac{\left( \frac{\mu_g}{\mu_l} - 1 \right)}{\left( \mu_g - 1 \right)} \) \( P_l = 3 \frac{\left( \frac{1.5}{2} - 1 \right)}{\left( 1.5 - 1 \right)} = 3 \frac{\left( 0.75 - 1 \right)}{\left( 0.5 \right)} = 3 \frac{(-0.25)}{(0.5)} = -1.5 D \)