Colour spectrum Sunlight is not colourless, but is made up of all the colours of the rainbow: the spectrum of light. We see these colours when a rainbow forms. In fact, only three, red, green and blue (called primary colours), are needed for our eyes to see every colour there is. Many different colours can be made by mixing together primary colours in different amounts.
Using a prism
The different colours of light can be seen when white light is split up using a prism, an angled block of transparent material such as clear glass or plastic. As the light waves pass into and then out of the prism they are bent or refracted. Longer waves of red light refract least. Shorter waves of violet light refract most. The other colours, orange, yellow, green and blue, are spread out between them.
A raindrop works as a natural, tear-shaped prism. Millions of raindrops split sunlight and form a rainbow in the sky.
A rainbow is the effect produced when millions of raindrops split sunlight into its component colours.
Only three colours, red, green and blue (called primary colours), mixed together are needed for our eyes to see every colour there is.
Find the answer