Question

an astronomical telescope with small amplitude has an objective whose power is 2 diopters. the lens is placed 60 cm from the eye piece, when the telescope is adjusted for minimum eye strain. calculate the angular magnification of telescope.

Answer 1

$\text{For lens:}$

$D_l = 2; f_o = \frac{1}{D}=0.5m$

$\text{For eyepiece}$

$f_e +f_o = h$

$h = 60cm=0.6m$

$f_e = 0.1m$

$\text{angular magnification }M$

$M= \frac{f_o}{f_e}= 5$

$\text{Answer :angular magnification }M= 5$