Focal length of objective and eye piece of telescope are $200 \; cm$ and $4 \; cm$ respectively. What is the length of telescope for normal adjustment (in $; cm$)?

The focal length of the objective and eyepiece of a telescope are respectively $200 \, cm$ and $5 \, cm$. The maximum magnifying power of the telescope will be

$A$ telescope has an objective lens of focal length $144\, cm$ and an eyepiece of focal length $6\, cm$. Find the magnifying power of the telescope for normal adjustment.

In an astronomical telescope in normal adjustment,a straight black line of length $L$ is drawn on the inside part of the objective lens. The eyepiece forms a real image of this line. The length of this image is $I$. The magnification of the telescope is:

$(a)$ $A$ 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?
$(b)$ If this telescope is used to view the moon,what is the diameter of the image of the moon formed by the objective lens? The diameter of the moon is $3.48 \times 10^{6} \; m$,and the radius of the lunar orbit is $3.8 \times 10^{8} \; m$.

If an astronomical telescope has objective and eye-piece focal lengths of $200 \; cm$ and $4 \; cm$ respectively,then the magnifying power of the telescope for normal vision is: