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Electrostatic Charge

Photocopier.

A photocopier uses electrostatic charge to produce a copy.

The original (the page you want copied) is placed onto a sheet of glass.
An image of this page is projected onto a positively charged drum.

The drum has a coating which conducts electricity when light falls on it.
The parts of the drum which are lit by the projected image
lose their electrostatic charge when they start to conduct.

A black powder (called toner) is negatively charged.
The toner is attracted to the positively charged parts of the drum.
The drum rotates and rolls against a piece of copier paper.
The toner is transferred from the drum to the paper
making a black and white image of the original.

Finally, the paper is heated which makes the toner stick to it.
This is called "fixing" the image.
When you use a photocopier
you can feel that the copier paper is still warm.

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Copyright © 2008 Dr. Colin France. All Rights Reserved.