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A plano-convex lens made of a material with a refractive index of 1.6 has a power of +4.0 D . What is the radius of curvature of its curved surface?

Options

  1. A15 cm
  2. B30 cm
  3. C40 cm
  4. D0.15 cm

Correct answer

A. 15 cm

Step-by-step solution

Using the lens maker's formula: P = ( - 1) ( 1 R₁ - 1 R₂ ) For a plano-convex lens, the radius of curvature of the plane surface is infinity. Let R₁ = R and R₂ = . P = - 1 R Given P = +4.0 D and = 1.6 : 4.0 = 1.6 - 1 R 4.0 = 0.6 R R = 0.6 4.0 = 0.15 m R = 15 cm Answer: 15 cm

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