The length of a telescope is $36 \ cm$. The focal lengths of its lenses can be

In a simple telescope,the focal length of the objective lens is $f_o = 60 \ cm$ and the focal length of the eyepiece is $f_e = 5 \ cm$. If the rays coming from the object make an angle of $2^\circ$ at the objective,then the angular magnification (angular size of the image) is ........... $^\circ$.

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

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:

Consider a refracting telescope whose objective has a focal length of $1 \ m$ and the eyepiece has a focal length of $1 \ cm$. The magnifying power of this telescope will be . . . . . . .

The magnifying power of an astronomical telescope is $8$ and the distance between the two lenses is $54 \, cm$. The focal lengths of the eye lens and the objective lens will be respectively: