Reflection of Light

There are two basic types of telescopes, refractors and reflectors. The refractor telescope uses a lens to gather and focus light. The reflector telescope uses a mirror to gather and focus light. All modern research telescopes and large amateur ones are of the reflector type because of its advantages over the refractor telescope.

On 25th December 2021, NASA launched the most advanced telescope that has ever been created. A telescope that can potentially change our understanding of the universe. This structure, which somewhat looks like a giant honeycomb on a boat is the James Webb Space Telescope or JWST for short. So, what is it that makes this telescope the most advanced one yet? James Webb Space Telescope is a reflecting telescope that uses a combination of curved mirrors that reflect light and form an image.

The diagram below shows light rays in a reflecting telescope.

(i) Describe what the mirrors and the eyepiece do to the light rays to form an image of a distant star.

(ii) Explain an advantage of using a telescope instead of the naked eye to look at stars.

Here is a diagram of an optical fibre.

(i) What is the name given to the dotted line on the diagram?

(ii) Where the ray of light touches the edge of the optical fibre, it is reflected. Draw the reflected ray onto the diagram.