### KS3 Physics

Energy
Motion and Forces
Waves
Electricity and Electromagnetism
Matter
Space Physics

# Static Electricity

When looking at static electricity, we can break it up into two words. Static means not moving and electricity refers to the transfer of energy by charged particles.

So, the definition of static electricity is the build-up of electrical charge within or on the surface of an insulated object.

## Atoms and Electrons

Everything around us is made up of atoms. An atom by itself is electrically neutral, which means that it has no overall electrical charge. However, atoms contain charged particles.

There are two types of charges:

• Positive charges
• Negative charges

Atoms contain protons in the nucleus, the centre of the atom, which is positively charged. They also contain electrons surrounding the nucleus of the atom, which are negatively charged.

This means that when we look at positive and negative charges, we can look inside an atom and see positive charges as protons and negative charges as electrons. But keep in mind:

• When an atom gains an electron, it becomes more negatively charged
• When an atom loses an electron, it becomes more positively charged

Atoms that have the same number of protons and electrons have no charge, just like this atom:

This atom has 8 protons and 8 electrons, which means it is a neutral atom, so it has no overall charge.

“For static electricity to occur, we need a build-up of charge. When you rub two insulating materials together, electrons will transfer from one material to the other.

## Electric Field

A charged object will create an electric field, which is an area surrounding an electric charge that can influence other charged particles. Although you cannot see an electric field, when another charged object enters the field, a non-contact force acts on it.

• Non-contact forces are forces that act on an object even when they are not touching

As the charged objects don’t need to touch for these forces to act, it is considered a non-contact force.

### Example

A balloon and a jumper both have equal amounts of positive and negative charges.

When you rub the balloon on the jumper, electrons move from the jumper to the balloon.

The balloon now has more electrons and remember, electrons have a negative charge, which means the balloon will have an overall negative charge. The jumper lost electrons, so it will be positively charged. This means the balloon will have an overall negative charge and the jumper will have an overall positive charge.

Although the balloon and jumper are equally charged, they are oppositely charged.

### Opposite charges attract

Now, remember, opposite charges attract. As the balloon has an overall negative charge and the jumper has an overall positive charge, the balloon and the jumper will be attracted to each other.

You can see how the balloon and the jumper are attracted to each other in the diagram below.

The neutral green balloon has an equal number of negative and positive charges, so it is not attracted to the jumper.

When the negatively charged balloon is placed next to a neutrally charged wall, it repels the electrons in the wall and becomes attracted to the positively charged parts of the wall.

Remember:

• Two negative charges will repel each other
• Two positive charges will repel each other

## Static Electricity and Lightning

Lightning is caused by static electricity. This occurs when there’s an accumulation of positive and negative charges in a cloud. Electrons move from one area to another, creating the visible lightning.

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