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Question
Draw a labeled ray diagram of a reflecting telescope. Mention its two advantages over the refracting telescope.
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Solution
Reflecting Telescope,
Its two advantages over Refracting telescope:
1. It reduces the spherical aberration and forms a clear focused image.
2. It doesn’t require a lens of very large aperture as refracting type requires that cannot be manufactured easily.
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Draw a labelled ray diagram of an image formed by a refracting telescope with the final image formed at infinity. Derive an expression for its magnifying power with the final image at infinity
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| There are two types of optical instruments: Microscopes and Telescopes. Microscopes are used to magnify very tiny objects whereas telescopes are used to study distant objects. Both of them deploy convex lenses. In his telescope, Newton used a large parabolic mirror to collect light from the stars and reduce aberrations. |
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What is the difference between a compound microscope and an astronomical telescope (refracting type), as far as their lenses are concerned?
Useful Constants & Relations:
| 1 | Charge of a proton | e | 1.6 × 10-19 C |
| 2 | Speed of light in vacuum | c | 3 × 108 ms-1 |
| 1 u = 931 MeV | |||
For a terrestrial telescope used to observe objects on Earth such as mountains, trees, or players in a stadium, the final image must be:
In an astronomical (refracting) telescope, the objective lens has:
In the working idea of a telescope's magnifying power, the beam of incident rays is inclined at an angle \[\alpha\] with the principal axis, while the emergent beam is inclined at a greater angle \[\beta\]. This produces:
According to Rayleigh's criterion for the angular separation between two resolvable objects, the correct relation is:
Which type of telescope uses two convex lenses, with a large objective and a small eyepiece?
Which type of telescope uses a converging lens as eyepiece and gives an inverted image?
