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AP EAMCET2008PhysicsRay Optics

The refractive index of a material of a planoconcave lens is 5 / 3 , the radius of curvature is 0.3 ~m . The focal length of the lens in air is

Options

  1. A-0.45 ~m
  2. B-0.6 ~m
  3. C-0.75 ~m
  4. D-1.0 ~m

Correct answer

A. -0.45 ~m

Step-by-step solution

Lens maker's formula 1 f =( -1) [ 1 R₁ - 1 R₂ ] where, R₂= , R₁=0.3 ~m array llrl & & 1 f & = ( 5 3 -1 ) ( 1 0.3 - 1 ) & & 1 f & = 2 3 1 0.3 or & & f & =0.45 ~m array

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