If the focal lengths of the objective and eyepiece of an astronomical telescope are $200 \, cm$ and $4 \, cm$ respectively,then the length of the telescope for normal adjustment is ......... $cm$.

The focal length of the objective and eye lens of an astronomical telescope are $2 \, m$ and $5 \, cm$ respectively. The final image is formed at $(i)$ the least distance of distinct vision and $(ii)$ infinity. The magnifying power in both cases will be:

$A$ 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

The astronomical telescope consists of an objective lens and an eye-piece. The focal length of the objective is:

Four convergent lenses have focal lengths $100 \, cm, 10 \, cm, 4 \, cm$ and $0.3 \, cm$. For a telescope with maximum possible magnification,we choose the lenses of focal length

The minimum magnifying power of a telescope is $M$. If the focal length of its eye lens is halved, the magnifying power will become: