An astronomical telescope of ten-fold angular magnification has a length of $44\, cm$. The focal length of the objective is.......$cm$

Four lenses of focal length $+ 15\, cm, + 20\, cm, + 150\, cm$ and $+ 250\, cm$ are available for making an astronomical telescope. To produce the largest magnification,the focal length of the eye-piece should be.....$cm$

An astronomical telescope has a magnifying power $10$. The focal length of the eyepiece is $20 \, cm$. The focal length of the objective is.....$cm$.

If the focal lengths of the objective and eyepiece of an astronomical telescope are $200 \, cm$ and $4 \, cm$ respectively,what will be the magnifying power for distant vision (normal adjustment)?

If a telescope is reversed,i.e.,viewed from the objective side,what happens to the appearance of the object?

An astronomical telescope has a large aperture to