$A$ 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 . . . . . .

An observer looks at a tree of height $15 \ m$ with a telescope of magnifying power $10$. To him,the tree appears

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

$A$ 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.......$\text{cm}$.

An astronomical telescope has an angular magnification of magnitude $5$ for distant objects. The separation between the objective and the eyepiece is $36 \, cm$ and the final image is formed at infinity. The focal length $f_o$ of the objective and the focal length $f_e$ of the eyepiece are:

The focal lengths of the objective and eye-piece of a telescope are $100 \ cm$ and $2 \ cm$ respectively. The moon subtends an angle of $0.5^o$ at the eye. If it is viewed through the telescope, the angle subtended by the moon's image will be......$^o$.