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NEET 1999 (AIPMT) · Spherical Surfaces & Thin Lenses

Spherical Surfaces & Thin Lenses question from NEET 1999 (AIPMT)

Q110NEET 1999 · AIPMTEasy

Spherical Surfaces & Thin Lenses

A plano-convex lens is made of material of refractive index 1.6. The radius of curvature of the curved surface is 60 cm60\text{ cm}. The focal length of the lens is

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Answer: (b)

  1. For a plano-convex lens R2=∞R_2 = \infty: 1f=μ−1R\frac{1}{f} = \frac{\mu - 1}{R}
  2. f=601.6−1=600.6=100 cmf = \frac{60}{1.6 - 1} = \frac{60}{0.6} = 100\text{ cm}
  3. So the answer is (b) 100 cm.
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