P7B Using Telescopes

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  • Created by: Sonya
  • Created on: 18-04-11 10:29

WHY DO WE USE TELESCOPES?

Telescopes are used to magnify things like stars and comets in space, that are not visible with the naked eye. Most objects in the sky are very dim. Telescope effectively collects more light and converges it for our viewing.

WHAT ARE LENSES?

Lenses are usually made from glass. Light entering the glass slows down and so it changes direction- this is called refraction.When the light leaves the glass it speeds up again, so it changes direction again. It bends the other way.

CONVERGING & DIVERGING LENSES:

- A convex lens is thicker in the middle than at the edges. 

- Parallel rays entering a convex lens are refracted and come to a point called the focus - we say they converge.

HOW DOES A CONVEX LENS FORM AN IMAGE?

A convex lens refracts the rays of light coming from a star so that they all pass through a single point. This point is called the image of the star- to our eye it looks as

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