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Question
A compound microscope has an objective of focal length 1.25 cm and eyepiece of focal length 5 cm. A small object is kept at 2.5 cm from the objective. If the final image formed is at infinity, find the distance between the objective and the eyepiece ?
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Solution
Distance between the objective and the eyepiece, L =
\[u_0 = - 2 . 5 \text {cm and } f_0 = 1 . 25 cm\]
\[\text { Now }, - \frac{1}{u_0} + \frac{1}{v_0} = \frac{1}{f_0}\] \[or \ v_0 = 2 . 5 cm\]
To find ue, we have:
\[v_e = \infty\text { and } f_e = 5 cm\]
Calculating using the same formula as above, we get:
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