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Manipal MET2017PhysicsRay Optics

A thin rod of length f 3 is placed along the optic axis of a concave mirror of focal length f , such that its image which is real and elongated just touches the rod, the magnification is

Options

  1. A1.5
  2. B2.5
  3. C3.5
  4. D4.5

Correct answer

A. 1.5

Step-by-step solution

u=P A=P C-A C=2 f- f 3 = 5 f 3 From mirror formula 1 f = 1 v + 1 u 1 v = 1 f - 1 u = 1 f - 3 5 f = 2 5 f Length of image C A^ =P A^ -P C= 5 f 2 -2 f= f 2 Magnification (m)= C A^ C A = f / 2 f / 3 =1.5

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