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

To produce a magnified erect image of a far object,along with a convex lens,we will require:

The magnifying power of a telescope can be increased by

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:

$A$ planet is observed by an astronomical refracting telescope having an objective of focal length $16 \, m$ and an eye-piece of focal length $2 \, cm$. Which of the following statements is correct?

$A$ Cassegrain telescope uses two mirrors of radii of curvature $25 \ cm$ and $16 \ cm$ separated by a distance of $2.5 \ cm$. The position of the final image of an object at infinity is