preproom.orgThe online science prep room
You are here: Home > Equipment > Colour Wheel
Equipment

Colour Wheel
AKA: Colour Mixing

Click for full size image
Click for full size image
Fig 1: Simple colour wheel disk available through Timstar
Fig 1
Fig 2
Fig 3

Summary

A wheel containing segments of colour is spun. The colours combine to create a white wheel.

Operation

These wheels are available from lab suppliers or can be made in various ways. Sticking to thin segments of primary colours (red, green and blue) pretty much guarantees a near white colour when spun quickly though you could experiment with other colours and lighter or darker pigments.

Just like colour mixing lights which some lab suppliers now stock, using a disk of just red and blue, magenta can be made. Red and green disks will make yellow and green and blue disks will make cyan.

Some schools opt for attaching a wheel to an electric drill but a hand turned wheel or low voltage motor works just as well and is probably a lot safer. Simply attaching a wheel to a board with a nail through the centre will provide sufficient turning when spun by hand.

The theory behind the colour wheel shows that white light is made up of many colours, seeing a red object just means that it reflects only the red part of the spectrum the remaining colours are absorbed. By spinning the wheel, you are in essence combining these colours to recreate white light.

Safety

 CautionThe contents of this page are for information only. Please refer to CLEAPSS or ASE safety advice and/or publications before undertaking any preparation, practical experiment or using any equipment featured on this site or any other.

Notes

The first rotating colour wheel was invented by Isaac Newton in the 1670s and comprised of seven colours selected only because there are seven notes in music, not because of the seven perceived colours in a rainbow.