Question

An astronomical telescope consists of 2 thin lenses set 36 cm apaert and has a mp a. Calculate the focal length of the lenses

Answer 1

In normal adjustment the image forms at infinity

So f o +f e

=36 , o is for objective and and e for eye piece

Also magnification is 8

8= fe/f o

f o =8f e

on solving we get fo

=32cmf e

=4cm