Question

How do telescopes work?

Answer 1

Hint: Telescope gathers light and helps us to be able to see distant objects clearly. Telescopes focus light using lenses and also use mirrors to gather light from the night sky and help us to see distant objects better. The mirrors or lenses which are used in a telescope are termed as “optics.” Powerful telescopes can see very dim things and things that are really far away.

Complete step by step answer:
Telescope is an optical device which enables us to see distant objects clearly. It provides angular magnification of distant objects. The problem in observing the objects in the night is that they are so far away and therefore appear extremely faint. The more light that we are able to collect with a telescope, the better we can see these objects at night. The light collecting ability of a telescope is determined by its diameter of lens or mirror they used, these are also known as its aperture.
Telescope can be divided into two categories: -
1. Refracting Telescope- These make use of lenses to view distant objects. These are again classified into two categories: - Astronomical telescope and Terrestrial Telescope.
2. Reflecting Telescope – These make use of converging mirrors to view distant objects. For example, Newtonian telescope and cassegrain telescope.

Telescopes focused light using pieces of curved, clear glass, called lenses and also use mirrors. Most of the telescopes today use curved mirrors to gather light from the night sky. The shape of the mirror or lens in a telescope can only decide how much light is concentrated by it. Mirrors of large aperture have high gathering power and absorb less amount of light than lenses of large aperture. This light is used to see distant objects when we see them through a telescope. This is the working of a telescope.
 The objective of a telescope should have a large aperture because then a much wider beam of light is incident on it and is converted into a small cone which on entering the eye, produces sufficient illumination on the retina. So even two distant faint stars which cannot be seen by naked eyes, become visible through such telescopes. This is the way that telescopes will work and help us to see distant objects clearly.

Note: The bigger the mirrors or lenses, the more light the telescope can gather. Light is then concentrated by the shape of the lens or mirror we used. The choice of lens and mirror in a telescope must be almost perfect. Lens and mirror can’t have any spots, scratches or other flaws otherwise the image is not sharp. If they do have such problems, the image gets blurry and is difficult to see.