Question

The focal lengths of the objective and eye plece of astronomical telescope are $100cm$ and $2cm$ respectively. The magnitude of magnifying power of telescope for adjustment is

• A. $54$
• B. $0.02$
• C. $50$
• D. $100$

Answer 1

Answer: (C)

$50$

The correct option is (C).

Given,

The focal length of the objective lens $f_o=100cm$

The focal lens of the eyepiece $f_e=2cm$

The magnifying power of a telescope can be given as the ratio of the focal length of the objective lens$f_o$ to the focal length of the eyepiece $f_e$ fo the telescope, hence

$M=\frac{f_o}{f_e}$

$M=\frac{100}{2}$

$M=50$ .