An astronomical telescope of ten fold angular magnification has a length of the 44 cm. The focal length of the objective is.

A. 4cm

B.40cm

C.44cm

D . 440 cm

(f_0/f_e )=10.

From the given magnification, we find that f₀ = 10 f_e.

Therefore, 10 f_e + f_e = 44 or 11 f_e = 44 or f_e= 4.

And focal length of the objective (f₀) = 44 - f_e = 44 - 4 = 40 cm.

Regards

Arun (askIITians forum expert)