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MHT CET 2025 (23 Apr, Shift 2) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from MHT CET 2025 (23 Apr, Shift 2)

Q30MHT CET 2025 · 23 APR · SHIFT 2Medium

Spherical Surfaces & Thin Lenses

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

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Answer: (c)

  1. PlPa=μμl−1μ−1=0.75−10.5=−12\frac{P_l}{P_a} = \frac{\frac{\mu}{\mu_l} - 1}{\mu - 1} = \frac{0.75 - 1}{0.5} = -\frac{1}{2}
  2. Pl=−12×3=−1.5P_l = -\frac{1}{2} \times 3 = -1.5 D (the lens becomes diverging).
  3. Magnitude 1.5 D, so the answer is (c) 1.5 D.
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