In a compound microscope, the magnified virtual image is formed at a distance of 25 cm from the eyepiece. The focal length of its objective lens is 1 cm. If the magnification is 100 and the tube leng…

Question

In a compound microscope, the magnified virtual image is formed at a distance of 25 cm from the eyepiece. The focal length of its objective lens is 1 cm. If the magnification is 100 and the tube length of the microscope is 20 cm, then the focal length of the eye-piece lens (in cm) is

Accepted Answer

Correct answer: 6.25. 6.25JEE Main 2020 For compound microscope the magnification when final image by eye-piece is formed at D=25 cm (least distance for clear vision) m= Lf_0(1+ Df_e)=100 ⇒ 201(1+ 25f_e)=100 ⇒1+ 25f_e=5 ⇒ 25f_e=4 ⇒f_e= 254=6.25 cm

$In a compound microscope, the magnified virtual image is formed at a distance of 25 cm from the eyepiece. The focal length of its objective lens is 1 cm . If the magnification is 100 and the tube length of the microscope is 20 cm, then the focal length of the eye-piece lens (in cm) is$

Solution

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