If we need a magnification of 375 from a compound microscope of tube length 150 mm and an objective of focal length 5 mm, the focal length of the eye-piece, should be close to:
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Question

If we need a magnification of 375 from a compound microscope of tube length 150 mm and an objective of focal length 5 mm, the focal length of the eye-piece, should be close to:

G1 Physics · Accepted Answer

Derived solution: Step 1: For a compound microscope use the objective and eyepiece magnifications, with M ≈ (L/fₒ)(D/fₑ) in normal adjustment (or the corresponding near-point form). Step 2: Substitute the values given in the question and apply the geometry/sign convention shown. Step 3: On simplification the result is 22 mm. Therefore the correct option is A.