The magnifying power of a telescope is 9. When it is adjusted for parallel rays. The distance between the objective and eyepiece is 20 cm. The focal length of its lenses are.
18 cm, 2 cm
m=f0fe=9
f0=9fe ... (i)
f0+fe=20 ... (ii)
By solving equation (i) and (ii)
fe = 2 cm, f0 = 18 cm