A microscope has an objective of focal length 2 cm, an eyepiece of focal length 4 cm and a tube length of 40 cm. If the distance of distinct vision of the eye is 25 cm, the magnification of the micros

Question

A microscope has an objective of focal length 2 cm, an eyepiece of focal length 4 cm and a tube length of 40 cm. If the distance of distinct vision of the eye is 25 cm, the magnification of the microscope is:

Vishal Gupta · Accepted Answer

B. m = \frac{L}{fo}\left(1 + \frac{D}{fe}ight) = \frac{40}{2}\left(1 + \frac{25}{4}ight) = 20 	imes 7.25 = 145; with the commonly used approximation m \approx \frac{L}{fo}\cdot\frac{D}{fe} = 20 	imes 6.25 = 125, which is the marked answer.

Ray Optics and Optical Instruments

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