Absorption Spectra

Describe how you would show that white light is a mixture of different colours.

What is the difference between different colours, apart from their appearance?

pic     D. Drumm

Why are sodium lamps (street lights) yellow?

If we shone white light through sodium vapour what would happen to it?

What is an absorption spectrum?

How do we know that the Sun is made mostly of hydrogen?

How was the element Helium discovered?

How can we tell how old stars are by analysing the light they emit?