CBSE Class 12 · 2006 · All India · Geometrical OpticsShort Answer

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Draw a labelled ray diagram of a reflecting type telescope. Write any one advantage it has over a refracting type telescope.

Solution

In a reflecting telescope a large concave (parabolic) mirror is the objective; it forms the image of a distant object, which is viewed through the eyepiece after reflection by a small plane mirror (Newtonian) or convex mirror (Cassegrain).
\textbf{Advantage over a refracting telescope:} the mirror objective produces \emph{no chromatic aberration} (reflection does not disperse light), and being supported all along its back it can be made very large, giving higher resolving power and a brighter image.

CBSE Class 12 Board · 2006 · All India · Subjective

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