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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:

1. 22mm
2. 12mm
3. 2mm
4. 33mm

Correct answer: 22mm

Solution

To achieve the desired total magnification of 375 with a compound microscope, we can use the formula for total magnification, which is the product of the objective magnification and the eyepiece magnification. Given the tube length and the focal length of the objective, we can calculate the required focal length of the eyepiece, which results in approximately 22 mm.

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