$A$ Galileo telescope has an objective of focal length $100\,cm$ and magnifying power $50$. The distance between the two lenses in normal adjustment will be......$cm$

$A$ terrestrial telescope is made by introducing an erecting lens of focal length $f$ between the objective and eyepiece lenses of an astronomical telescope. This causes the length of the telescope tube to increase by an amount equal to

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

What is the tube length of a telescope?

The magnifying power of a refracting type of astronomical telescope is $m$. If the focal length of the eyepiece is doubled,then the magnifying power will become:

The objective and eyepiece of an astronomical telescope are double convex lenses with refractive index $1.5$. When the telescope is adjusted to infinity, the separation between the two lenses is $16 \,cm$. If the space between the lenses is now filled with water and the telescope is again adjusted for infinity, then the present separation between the lenses is: (in $\,cm$)