Static Electricity 1:
What is Static Electricity?
Static electricity is when materials gain or lose electrons becoming positively or negatively charged. The charge created is what is referred to as Static Electricity.
The build up of static electricity is caused by Friction:
When two insulators are rubbed together, electrons are taken off one, and put onto the other.
This leaves positive static charge on one material (lost electrons) and negative static charge on another (gained electrons)
The way the elctrons move depends on the material.
Aceatae – becomes positive
Polythene – becomes negative
“Two things with opposite elctric charge are attracted to each other. Two things with the same electric charge will repel each other”
Static Electricity 2:
The Uses and Dangers of Static Electricity:
Paint Sprayers – even coating: The spray gun is given one charge and the object being painted another, providing an even coat and hardly any of the paint being wasted. No paint shadows either.
Dust Precipitators – clean emmisions: from factories and power stations. Dust becomes negatively charged while passing through a charged wire grid in chimney. Negatively charged dust sticks to earthed metal plates, evetually falling to the bottom and being removed.
Defibrillators – give elctric shocks: can restart a stopped heart. Consists of two paddles connected to a power supply when is pplaced on patients chest. Insulated handles. Charge passes from supply to paddles to make the heart contract.
Static Electricity 3:
Charge can build up: on clothes, synthetic materials when rubbed against other fabrics. Charge may become big enough to create a spark – not good near inflammable gases or fuel fumes.
Filling up petrol: as the fuel is flowing out of the filler pipe, static can build up. It may lead to a spark or possibly an explosion in dusty/fumy places (such as a petrol staton).
These dangers can be solved by earthing. This is when a charged object is connected to the groud using a conductor (such as copper wire). It provides an easy route for the static charges to travel to the ground. No charge builds up to create shocks or sparks.