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

$A$ giant refracting telescope at an observatory has an objective lens of focal length $15 \, m$. If an eyepiece of focal length $1.0 \, cm$ is used,what is the angular magnification of the telescope?

The focal lengths of the objective lens and the eye lens of a Galilean telescope are $30\, cm$ and $3.0\, cm$ respectively. The telescope produces a virtual,erect image of an object situated far away from it at the least distance of distinct vision from the eye lens. In this condition,the magnifying power of the Galilean telescope should be:

$A$ telescope has an objective lens of focal length $150\,cm$ and an eyepiece of focal length $5\,cm$. If a $50\,m$ tall tower at a distance of $1\,km$ is observed through this telescope in normal setting,the angle formed by the image of the tower is $\theta$,then $\theta$ is close to.....$^o$

Write a note on Cassegrain telescope.

An astronomical telescope has an eyepiece of focal length $5 \ cm$. The angular magnification in normal adjustment is $10$. When the final image is formed at the least distance of distinct vision $(25 \ cm)$ from the eyepiece,then the angular magnification will be: