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NEET 2022 (Phase 1) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from NEET 2022 (Phase 1)

Q62NEET 2022 · PHASE 1Easy

Spherical Surfaces & Thin Lenses

A biconvex lens has radii of curvature, 20 cm each. If the refractive index of the material of the lens is 1.5, the power of the lens is

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Answer: (c)

  1. Lens maker's formula: P=1f=(μ−1)(1R1−1R2)P = \frac{1}{f} = (\mu - 1)\left(\frac{1}{R_1} - \frac{1}{R_2}\right)
  2. P=(1.5−1)(10.2+10.2)=0.5×10=5 DP = (1.5 - 1)\left(\frac{1}{0.2} + \frac{1}{0.2}\right) = 0.5 \times 10 = 5\text{ D}
  3. So the answer is (c) +5 D.
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