An astronomical telescope has an angular magnification of magnitude 5 for distant objects. The separation between the objective and the eye piece is 36 cm and the final image is formed at infinity. The focal length $f_0$ of the objective and the length $f_e$ of the eye piece are

$f_0$ = 30 cm and $f_e$ = 6 cm

We know that, $f_0 + f_e = 36$ …(1)

Where $l$ = length of the tube = 36 cm

$\frac{f_0}{f_e}=m=5$ …(2)

Where m = magnification = 5

Solving (1) and (2) we obtain,

$5\, f_e + f_e = 36$

$⇒ f_e = 6 cm\, and\, f_0 = 5\, f_e = 30 cm$

∴ (D)