Question -
Answer -
Focal length of the objective lens, fo = 15 m = 15 × 102 cm
Focal length of the eyepiece, fe = 1.0 cm
(a) The angularmagnification of a telescope is given as:
Hence, the angularmagnification of the given refracting telescope is 1500.
(b) Diameter of the moon, d =3.48 × 106 m
Radius of the lunar orbit, r0 = 3.8 × 108 m
Let 
be the diameter of theimage of the moon formed by the objective lens.
The angle subtended by thediameter of the moon is equal to the angle subtended by the image.
Hence,the diameter of the moon’s image formed by the objective lens is 13.74 cm