Discover how to split white light into a rainbow of colours, just as Sir Isaac Newton did hundreds of years ago.
Astronomers are able to determine the composition of the the Sun by studying its light, with a technique known as spectroscopy. This technique can also be used to determine the chemicals elements present in a star or planet's atmosphere.
What you need
To do this activity you will need:
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sunlight
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a piece of card with a one millimetre wide slit cut into the middle
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a straight-sided glass filled with water
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a sheet of white A4 paper.
What to do
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Fill a straight-sided glass with water and tape the card onto the side of the glass.
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Place the white sheet of paper close to a window where sunlight is entering.
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Stand the glass on the paper with the slit facing towards the Sun.
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The sunlight should pass through the slit and split into its colour components as it enters the glass. The colours should appear on the paper.
What's happening?
White light is a mixture of many different colours. Sir Isaac Newton proved this more than 300 years ago when he directed a beam of sunlight through a slit and prism in a darkened room in 1666.
The prism bent, or refracted, the white light so that it fanned out into a rainbow (spectrum) of colours.
Splitting light using prisms is known as spectroscopy. Each chemical element has a unique signature when its light is split up.
Astronomers use spectroscopy to determine what planets and stars are made of by examining their light.
See other activities from Physics activities.
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