$A$ small telescope has an objective lens of focal length $140 \ cm$ and an eyepiece of focal length $5 \ cm$. The magnifying power of the telescope for viewing a distant object when the telescope is in normal adjustment is . . . . . . .

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 .......... $^o$.

Consider a refracting telescope whose objective has a focal length of $1 \ m$ and the eyepiece has a focal length of $1 \ cm$. The magnifying power of this telescope will be . . . . . . .

The magnifying power of a telescope can be increased by

The diameter of the moon is $3.5 \times 10^{3} \, km$ and its distance from the Earth is $3.8 \times 10^{5} \, km$. It is viewed by a telescope with objective and eyepiece focal lengths of $4 \, m$ and $10 \, cm$ respectively. What is the angular diameter of the image of the moon in degrees?

The magnifying power of an astronomical telescope for relaxed vision is $16$. On adjusting,the distance between the objective and eye lens is $34\, cm$. Then the focal length of the objective and eye lens will be respectively: