P1.4 - Reflecting telescopes

Question 1

Why would refracting telescopes or other telescopes using an objective lens be likely to produce a fainter image than a telescope using a mirror?

Answer 1

Because light isn’t only refracted at boundaries, some of it is also reflected. This means that whenever light passes through a lens, some of the light gets reflected. This can make the image very faint, which is particularly problematic when the star is already quite far away/faint.

Question 2

What two things happen when light waves reach a boundary between different materials

Answer 2

The waves reflect and refract.

Question 3

What does the curved primary mirror do

Answer 3

Focuses parallel light rays from a distance object to an image in the same way as objective lens in a refracting telescope.

Question 4

What happens to the image when the light rays have been focused by the primary mirror

Answer 4

They are magnified by the eyepiece lens