An astronomical telescope has an angular magnification of magnitude 5 for distant object. The separation between the objective and the eyepiece is 36 cm and the final image is formed at infinity. The focal length `f_(0)` of the objective and the focal length `f_(0)` of the eyepiece are

Options

A. `f_(o) = 45" cm and " f_(e) ` = -9 cm
B. `f_(o) = 7.2" cm and " f_(e) ` = 5 cm
C. `f_(o) = 50" cm and " f_(e) ` = 10 cm
D. `f_(o) = 30" cm and " f_(e) ` = 6 cm

Answer

D

Explanation

`m = (f_(O))/(f_(e)) = 5 and L = f_(o) + f_(e) = 36`
`rArr 5 f_(e) + f_(e) = 36 rArr f_(e) = 6 cm, f_(O) = 30 cm `