Physics can be difficult to learn, but this blog aims to help you get into physics by connecting your GCSE physics lessons with things you see in the world around you.

## Thursday, 6 October 2011

### A Perfect Copy

Photocopiers are a bit of a mystery aren’t they? A big, hot box with flashing lights and whirring noises that can churn out copies of your document almost faster than you can blink! But how does it work? Well, we’re back to that old favourite, electricity again!

It’s all about static electricity once more, which is the small charge which can make balloons stick to the wall (or cats) and can even make your hair stand on end! It’s easy to create a static charge on plastic items like rulers, and if you’ve ever felt a spark from a metal object that’s thanks to static too.

Sometimes these charged objects are fun, but they can also be hazardous too, like if you were to experience a spark from a static charge when you were near to fuel, for example. This could get very explosive very fast. But it can also be useful and in this case, it’s vital to making copies – fast. Let’s lift the lid and see what happens inside.

A plate inside the photocopier is negatively charged all over, and this is the centre of the copying system. That bright light you see when the copier makes the copy is because the machine relies on a projection of the image you’re copying. And that image gets projected onto the charged plate. It’s made of a special kind of material so that the light areas lose their charge, but the dark areas keep it.

The powdered ink (toner) is then applied to the plate, and it sticks to the negatively charged bits, where the dark on the image is. A piece of paper is then pressed onto the plate. It’s heated so that the powdered ink melts and sticks to the paper.

All of this happens in super quick time, so it seems incredible that so many processes are involved! And it’s all thanks to the humble electric charge.