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Electrostatic Charge

Charging.

Insulators can transfer charge by friction.
When the surface of one insulator rubs against another,
electrons can be transferred.

The insulator which gains electrons will get a negative charge,
the insulator which loses electrons will get a positive charge.

It is most important to know that
it is only the negative electrons which can move.
Positive charges (protons) cannot move
because they are stuck inside the nuclei of the atoms of the material.

For example, if polythene (a type of plastic) is rubbed with a dry cloth,
electrons are transferred from the cloth to the polythene.
The polythene gains electrons and becomes negatively charged,
the cloth loses electrons and becomes positively charged.

It is not possible to predict in advance
which way the electrons will go for a certain material.
The same cloth, when rubbed against acetate (a different type of plastic)
will gain electrons and become negatively charged,
leaving the acetate with a positive charge.

If you want to know more about electrons and protons,
see the GCSE Chemistry site.

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