What do you get if you mix a camera with a watch? You get this - the world's first wrist camera watch.

It can tell the time just like any other watch, but it can also take photographs using new digital technology.

The watch is smaller than a roll of film, and it doesn't need any film at all.

So how does the watch take a photograph? Well, it's all down to a very clever microchip inside. The chip contains lots of little squares, commonly known as pixels.

Pixels act a bit like bottles which fill up with light.

The light enters through this tiny lens.

Imagine that this milk represents the light going into the pixel.

Just a tiny drop...

...and you can see that there's not much change.

But if we put a lot of milk (light) in, it's much lighter and much brighter.

The same process happens across loads and loads of tiny pixels until eventually, a picture is created.

Once you've captured your image, you can send it to your computer to print out. It does this using an invisible ray of light called infra red.

The exchange between the camera and the computer works a bit like a game of battleships.

Fearne's board represents the wrist camera and its final image.

And Kate's board represents the computer. If Fearne tells Kate information about every square, she'll be able to recreate the image without seeing it.

And eventually... Eureka!

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