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 fo of the objective and fe of the eye-piece are respectively

Question

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 fo of the objective and fe of the eye-piece are respectively (A) 45 cm and 9 cm (B) 50 cm and 10 cm (C) 7.2 cm and 5 cm (D) 30 cm and 6 cm

Tardigrade Admin · Accepted Answer

(fo/fe)=5 fo=5fe fo+fe=36 5fe=6 cm and fe=30 cm

Q. An astronomical telescope has an angular magnification of magnitude $5$ for distant objects. The separation between the objective and the eye-piece is $36 c m$ and the final image is formed at infinity. The focal length $f_{o}$ of the objective and $f_{e}$ of the eye-piece are respectively

45 cm and 9 cm

50 cm and 10 cm

7.2 cm and 5 cm

30 cm and 6 cm

5 cm and 7.2 cm

$\frac{f _{o}}{f _{e}} = 5$
$f_{o} = 5 f_{e}$
$f_{o} + f_{e} = 36$
$5 f_{e} = 6 c m$ and $f_{e} = 30 c m$

Q. An astronomical telescope has an angular magnification of magnitude 5 for distant objects. The separation between the objective and the eye-piece is 36cm and the final image is formed at infinity. The focal length fo​ of the objective and fe​ of the eye-piece are respectively