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Gallery 3

Can you see a Rainbow?

A glass bead panel and instruction text

Rainbows can be created when white light is refracted within prism-like water droplets and glass beads.

How it works

Walk around in front of a panel of glass beads and notice how a rainbow forms, as tiny glass beads (similar to raindrops) refract white light into a rainbow of colours.

Things to try or ask around the exhibit

  • Walk around on the coloured carpet tiles, to see where you can get the 'best' looking rainbow.
  • Do adults see rainbows in different parts of the panel compared to children?
  • Where is the spotlight located?
  • When you see a rainbow in the sky, where is the Sun usually located?

Background

When you shine a light at the tiny glass spheres you produce a rainbow very much like a natural one. Usually, light from the Sun is reflected (bounced) from the back of the raindrops to our eyes. The light is also refracted (bent) as it enters and leaves the raindrop. Each colour is refracted a different amount by the raindrops so the sunlight is split into the different colours.

Each drop produces all of the different colours, but wherever you stand, you only see one colour from each drop. Violet light is bent the most and red light the least. If red light from a particular raindrop enters your eye, then violet light from the same raindrop will not hit your eye but will ‘go over your head’. In order to see violet light you need to look at the light coming from raindrops that are lower in the sky. This is why red is on the outside of the rainbow and violet is on the inside.

Finding the science in your world

In this exhibit the ‘raindrops’ are tiny, solid glass beads, the same as the ones that make road signs reflective.

The best time to see a rainbow in the sky is with the Sun low in the sky behind you and rain in the distance ahead. The raindrops act like prisms and split sunlight into the range of colours that we see.