Newton colour wheel experiment with Fizzics Education

# Newton colour wheel

### You will need:

• Coloured pens, or a coloured printer.
• Paper
• One nail
• Pencil
• Cardboard
• Glue
• Wooden skewer or nail

1

Cut out a round piece of paper and divide the wheel into eight equal sized segments.

2

Colour in the segments in the order of the colours of the rainbow;

Red | Orange | Yellow | Green | Blue | Indigo | Violet

*It’s ok if you can’t get the ‘perfect’ colours for indigo & violet, just use purple.

3

Glue the picture on some cardboard and allow to dry.

4

Piece the middle of the disc with a nail or wooden skewer.

5

Whilst watching the coloured wheel, spin the kebab stick between fingers… what colour do you see? Why?

6

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### Why Does This Happen?

White light is comprised of all the colours of the visible spectrum.
i.e. red, orange, yellow, green, blue, indigo and violet… as well as the shades in between.

Spinning the disc mixed all the different wavelengths of coloured light together, creating white light. The faster you move the disc, the more white light you see. This process is call colour addition.

Colour subtraction occurs when substances that absorb light, such as paint, are mixed together. Mixing coloured paint eventually produces black paint, whereby all visible light is absorbed.

## 5 thoughts on “Newton colour wheel”

1. Sarah says:

How to measure how far a light goes for students

1. Ben Newsome says:

Hi Sarah!

This is a tricky one, as light travels across our Universe. However, light does reduce in intensity due to the inverse-square law, whereby the light intensity is inversely proportional to the square of the distance from the source (i.e. it reduces very quickly!). Perhaps try using a light meter using your phone (or from an electronics store)… you could place this at the end of different length tubes from a light source and you could measure this effect. Good luck!

2. Becky says:

My teacher said light traveled in straight lines but then what is refraction if light doesnâ€™t bend

1. Ben Newsome says:

Great question Becky!
This is all about the angle at which the light is travelling when it reaches the edge of another medium (eg, moving from water into air). A way to think about this is to try a quick activity with your friends;

1st steps of the activity
– Put a tape along the ground
– Stand shoulder to shoulder with three friends
– Someone gives you a broomstick for you all to hold together
– March together at the same pace towards the tape on the ground

… Whoever reaches the tape line first has to make a turn

What happens next?
… If you all reach the tape line at the same time, no-one has to turn and you all keep walking in a straight line
… If one of your friends gets to the tape line first, they have to make a turn and the others follow closely behind in the same direction (notice the last person has to walk fast to catch up?). The group is now travelling together at a different angle.

What has this got to do with light?
The reason light can bend is due to changes in density and the angle that light reaches the new material.
More dense materials slow light down whilst less dense materials allow light to travel faster.

– If there is no different in the angle that light is travelling compared to the edge of the material, the light continues in a straight line with just a change in speed.
– If there is a difference in angle, the light will bend towards the more dense substance.