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. `45cm` and `-9 cm`
B. `50 cm` and `10 cm`
C. `7.2cm` and `5 cm`
D. `30cm` and `6cm`

Answer

D

Explanation

`m =- 5 =- (f_(0))/(f_(e)) rArr f_(0) = 5f_(e)`
`L = f_(0) +f_(e) = 36`
`sigma f_(e) = 36 rArr f_(e) 6cm, f_(0)=5f_(e) = 30cm`