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MHT CET202122 Sep 2021Morning ShiftPhysicsRay OpticsActual

A biconvex lens ( R ₁= R ₂=30 ) has focal length equal to the focal length of concave mirror. The radius of curvature of concave mirror is [Refractive index of material of lens =1.6]

Options

  1. A30 cm
  2. B40 cm
  3. C50 cm
  4. D20 cm

Correct answer

C. 50 cm

Step-by-step solution

For a biconvex lens aligned & 1 f =( -1) ( 1 R ₁ - 1 R ₂ ) & =(1.6-1) ( 1 30 + 1 30 ) & =0.6 2 30 = 1.2 30 & f = 30 1.2 =25 ~cm aligned Radius of concave mirror =2 f =50 ~cm

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