Sunlight is white light

The idea

Sunlight is made up of seven colours: an identical prism placed inverted recombines the spectrum into white light; any light giving a spectrum similar to that of sunlight is called white light.

Can the colours be put back?

A prism splits white sunlight into colours. A scientist places a second, identical prism upside down after the first.

What will come out of the second prism?

• A beam of white light
• Even more colours
• No light at all

Newton's two prisms

Press Next step.

Seven colours make white

Newton could not split any single colour further. But with the second prism upside down, all the colours came together as white light. So sunlight is made up of seven colours.

Sunlight is made up of seven colours: an identical prism placed inverted recombines the spectrum into white light; any light giving a spectrum similar to that of sunlight is called white light.

Notes

Sunlight is made up of seven colours: an inverted identical prism recombines the spectrum into white light. Light giving a spectrum similar to sunlight's is called white light.

Check yourself

Newton placed a second identical prism in an inverted position. What emerged from it?

This observation gave Newton the idea that sunlight is made up of…

Any light that gives a spectrum similar to that of sunlight is often called…

Newton tried to split a colour of the spectrum further with another similar prism. What happened?

• More colours than the first prism made. Newton could not get any more colours using another similar prism, and the inverted prism gave white light.
• A beam of white light — correct. Yes!
• A single red beam. All the colours of the spectrum passed through the second prism and a beam of white light emerged.
• one colour. The prism splits it into a spectrum, and the inverted prism recombines the colours into white light. So sunlight is made up of seven colours.
• two colours. Sunlight is made up of seven colours.
• seven colours — correct. Yes!
• white light — correct. Yes!
• coloured light. Light that gives a spectrum similar to that of sunlight is often called white light.
• dispersed light. Dispersion is the splitting of light. Light giving a spectrum like sunlight's is called white light.
• Each colour split into seven more colours. Newton could not get any more colours.
• He could not get any more colours — correct. Yes!
• Each colour turned white. He could not get any more colours; the colours stayed as they were.