Static Electricity

We can break up static electricity into two words. Static means ‘not moving’ and electricity refers to the transfer of energy by charged particles.

Therefore, static electricity is defined as the build-up of electrical charge within or on the surface of an insulated object. The charges are called ‘static’ because they remain in nearly a fixed position within or on the surface of the object until they are given a path to escape.

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

Like charges repel and unlike charges attract.

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

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 are neutral, just like this atom:

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

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

Charge by Friction

When two objects are rubbed together, electrons can be transferred from one uncharged object to another. The objects can then become electrically charged.

before any interaction, both a balloon and a jumper 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 that the balloon will have an overall negative charge. The Jumper lost electrons, so it 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 yellow balloon and the jumper will be attracted to each other. You can see this in the diagram below.

The green balloon, being neutral, has an equal number of negative and positive charges, so it isn’t attracted to the jumper.

When a negatively charged balloon is placed next to a neutrally charged wall, it pushes away (or repels) the electrons in the wall’s surface. This causes a positive charge on the wall’s surface, which attracts the balloon.

You can try this experiment out for yourself here.

In summary, always 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. It happens when there’s an accumulation of positive and negative charges within a cloud. The movement of electrons from one area of the cloud to another produces the visible flash we recognise as lightning.