If $F_o$ and $F_e$ are the focal lengths of the objective and eyepiece respectively of a telescope,then its magnifying power will be

When the tube length of an astronomical telescope is increased,its magnifying power will .......

The diameter of the moon is $3.5 \times 10^3 \, km$ and its distance from the Earth is $3.8 \times 10^5 \, km$. Find the angle subtended by the moon at the eye when viewed through a telescope. The focal length of the telescope's objective is $4 \, m$ and the focal length of the eyepiece is $10 \, cm$. The angle is .......... $^o$.

$A$ telescope has an objective of focal length $100 \ cm$ and an eyepiece of focal length $5 \ cm$. The least distance of distinct vision is $25 \ cm$. The telescope is focused for distinct vision on a scale $3 \ m$ away from the objective. The magnification produced is . . . . . .

The magnifying power of an astronomical telescope is $8$ and the distance between the two lenses is $54 \, cm$. The focal lengths of the eye lens and the objective lens will be respectively:

$A$ Galilean telescope has an objective and an eyepiece of focal lengths $200 \, cm$ and $2 \, cm$ respectively. The magnifying power of the telescope for normal vision is