Why Did the Colours Change?

White light might look colourless, but it contains many different wavelengths of visible light — the colours we see in a rainbow.

When white light reaches one of your Colour Smashers, something interesting happens.

The paddle doesn't simply add colour to the light.

It acts as a colour filter.

What Does a Colour Filter Do?

A coloured filter allows some wavelengths of light to pass through while absorbing others.

For example, a yellow filter mainly allows red and green light through while absorbing much of the blue light.

The light that reaches your eyes therefore looks yellow.

So the colour you see depends on which wavelengths survive the journey through the filter.

What Happened When 

You Smashed Two Colours Together?

When you overlapped two paddles, the light had to travel through two filters.

The first filter removed some wavelengths.

Then the second filter removed some more.

Only wavelengths that could pass through both filters reached your eyes.

That's why overlapping the paddles created a new colour — and why the result may not have been what you predicted.

Why Did It Get Darker?

You may also have noticed that overlapping several paddles made the view darker.

That's because every filter absorbs some of the incoming light.

Add another filter and even less light may make it through.

Scientists call this subtractive colour mixing because wavelengths of light are being subtracted from the original white light.