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Manipal MET2020PhysicsRay Optics

A concave lens is kept in contact with a convex lens of focal length 20 cm . The combination works as convex lens of focal length 50 cm . The power of concave lens is

Options

  1. AP=-3.0 D
  2. BP=+3.0 D
  3. CP=-0.3 D
  4. DP=+0.3 D

Correct answer

A. P=-3.0 D

Step-by-step solution

Power of the combination P=P₁+P₂=P_ concave +P_ convex 100 50 =P_ concave + 100 20 or 2=P_ concave +5 or P_ concave =2-5=-3.0 D

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