The magnifying power of an astronomical refracting telescope in normal adjustment is given by:
$$m = \frac{f_o}{f_e}$$where:
- $f_o$ is the focal length of the objective lens
- $f_e$ is the focal length of the eyepiece lens
To increase the magnifying power $m$, one must increase the focal length of the objective lens ($f_o$) or decrease the focal length of the eyepiece ($f_e$). Hence, option 1 is the correct answer.
सामान्य समायोजन में खगोलीय अपवर्ती दूरदर्शी की आवर्धन क्षमता:
$$m = \frac{f_o}{f_e}$$जहाँ $f_o$ अभिदृश्यक लेंस की फोकस दूरी तथा $f_e$ नेत्रिका लेंस की फोकस दूरी है।