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In a microscope of tube length 10 cm two convex lenses are arranged with focal length of 2 cm and 5 cm. Total magnification obtained with this system for normal adjustment is (5)^ k . The value of k is _ _ _ _ .

Options

  1. A3.5
  2. B2
  3. C4
  4. D5

Correct answer

B. 2

Step-by-step solution

For a microscope in normal adjustment, magnification is given by M = L f_o D f_e where L is tube length (10 cm), f_o is objective focal length (2 cm), f_e is eyepiece focal length (5 cm), and D is least distance of distinct vision (25 cm). M = 10 2 25 5 = 5 5 = 25 = 5^2 Therefore, k = 2

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