Which one of the following telescopes contains only mirrors ?

[amp_mcq option1=”Galilean telescope” option2=”Keplerian telescope” option3=”Newtonian telescope” option4=”Schmidt telescope” correct=”option3″]

This question was previously asked in

UPSC NDA-1 – 2023

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A Newtonian telescope is a type of reflecting telescope that uses a concave primary mirror to collect and focus light, and a flat secondary mirror placed in the light path to redirect the light to an eyepiece positioned at the side of the telescope tube. The primary and secondary mirrors are the key optical components responsible for forming the image. It uses only mirrors for the main light path and image formation.

– Telescopes are classified as refractors (using lenses), reflectors (using mirrors), or catadioptric (using both lenses and mirrors).
– Galilean and Keplerian telescopes are types of refracting telescopes, using lenses.
– A Newtonian telescope is a type of reflecting telescope, using mirrors (a primary parabolic mirror and a secondary flat mirror).
– A Schmidt telescope (e.g., Schmidt-Cassegrain) uses both a corrector plate (lens) and mirrors.
– The question asks for a telescope containing *only* mirrors in its main optical path for image formation.

Reflecting telescopes, like the Newtonian, have advantages over refracting telescopes, such as the absence of chromatic aberration (color fringing) which occurs in lenses, and they can be made much larger since mirrors are supported from the back.

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