Question

Four lenses of focal length 15 cm, 20 cm, 150 cm and 250 cm are available for making an astronomical telescope. To produce the largest magnification, what should the focal length of the eyepiece be?

• A. $+15cm$
• B. $+20cm$
• C. $+150cm$
• D. $+250cm$

Answer 1

The correct option is A $+15cm$

$m=\frac{f_0}{f_e}$
for getting maximum magnification,
$f_0=250cm$
$f_e=15cm$