Static Electricity

What is static electricity?

• Everything we see is made up of tiny little parts called atoms.

• The atoms are made of even smaller parts. • These are called protons, electrons and neutrons. • They are very different from each other in many ways. • One way they are different is their "charge."

Protons have a positive (+) charge. Electrons have a negative (-) charge.

Neutrons have no charge.

Only electrons (-ve) move

• Atoms have the same number of electrons and protons.

• Then the atom has no charge, it is "neutral." • But if you rub things together, electrons can

move from one atom to another. • Some atoms get extra electrons. They have a

negative charge. • Other atoms lose electrons. They have a

positive charge. • When charges are separated like this, it is called

static electricity.

Attraction and Repulsion

• If two things have different charges, they attract, or pull towards each other.

• If two things have the same charge, they repel, or push away from each other.

• Only negative electrons can move - the positive remain fixed.

• Polythene becomes negatively charged.• Perspex becomes positively charged.• The closer the charges, the greater the force.

Electrostatic induction

• Experiment:Rub a balloon on your clothes. Then put it on the wall or ceilingSo that it stays there!

• This happens because the negative charge on the rubbed balloon repels some of the electrons in the ceiling away from the surface. This leaves the surface positively charged and so the negative balloon is attracted to the ceiling.

The separated charges in the ceiling are called INDUCED charges.

Earthing

• Conductors can be charged by induction• Insulators are charged by rubbing

• A charged conductor must be held by an insulated handle or stand.

• Earthing a charged:

Charging a conductor

Electrostatic Precipitator• Power stations and factories produce huge amounts of

smoke pollution. This cloud is a cloud of small dust particles or ash, it can be removed using static electricity

• Thin wires are stretched across the centre of the chimney: these wires are charged positively ~ 50 000V

• They cause the gas around them to charge or ionize• Due to this, the smoke particles are positively charged. • They are then repelled by the wires, towards the earthed

metal plates, where dust sticks.• A mechanical hammer hits the plates every few minutes

and the ash falls down into a bin.• This is used to make house bricks.

Made by Joseph Agius

&Kyle Cutayar

Class: 4.9