Question

Magnifying power of a telescope, when the final image is formed at infinity, can be increased by -

• A. Fitting objective lens of high power.
• B. Fitting eyepiece of high power.
• C. Fitting eyepiece of low power.
• D. None of these

Answer 1

The correct option is B Fitting eyepiece of high power.

The magnifying power of the telescope when the final image is formed at infinity is given as,

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

$\Rightarrow m=\frac{\frac{1}{f_e}}{\frac{1}{f_o}}=\frac{P_e}{P_o}$

So,

$m\propto P_e$ and $m\propto \frac{1}{P_o}$

Therefore, magnifying power of a telescope, when the final image is formed at infinity, can be increased by fitting eyepiece of high power and objective lens of low power.

Hence, option $\left(B\right)$ is the correct answer.