If the focal length of the objective lens is increased,then:

If a telescope is reversed,i.e.,viewed from the objective side,what happens to the appearance of the object?

$A$ telescope has an objective of focal length $50 \text{ cm}$ and an eyepiece of focal length $5 \text{ cm}$. The least distance of distinct vision is $25 \text{ cm}$. The telescope is focused for distinct vision on a scale $200 \text{ cm}$ away. The separation between the objective and the eyepiece is.......$\text{cm}$.

The aperture of a telescope is made large,because

$A$ Galileo telescope has an objective of focal length $100 \, cm$ and magnifying power $50$. The distance between the two lenses in normal adjustment will be....$cm$

$A$ small telescope has an objective of focal length $140 \ cm$ and an eyepiece of focal length $5.0 \ cm$. The magnifying power of the telescope for viewing a distant object is: