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.

Shows the interactions between magnets. Two green circles with positive signs facing each other are labelled 'Repel'. Two red circles with negative signs facing each other are also labelled 'Repel'. Lastly, a green circle with a positive sign and a red circle with a negative sign face each other and are labelled '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.

An illustration of an atom. At the centre, there's a nucleus composed of blue protons labelled 'Proton in nucleus' and green neutrons labelled 'Neutron in nucleus'. Orbiting the nucleus are red electrons on green paths, with one labelled 'Electron'.

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:

An atom with a central cluster of orange and red particles, possibly representing neutrons and protons. Surrounding the nucleus are two blue orbital paths with blue electrons positioned on them.

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.

An illustration of a grey jumper with the label 'PhET' at the collar, covered in red and blue symbols representing positive and negative charges. Next to the jumper is a yellow balloon with similar charge symbols, floating on a string.

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

An illustration of a grey jumper with the label 'PhET' at the collar, containing entirely red positive charge symbols. Beside the jumper is a yellow balloon, with a section showing a blue zigzag pattern, surrounded by red and blue charge symbols, floating on a string.

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.

An illustration featuring a grey jumper labelled 'PhET' at the collar, covered in red positive charge symbols. Next to it, a yellow balloon displays a strong negative charge, represented by blue negative charge symbols. To the right, a green balloon floats with four pairs of red positive and blue negative charge symbols.

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 on the wall’s surface. This causes a positive charge on the wall’s surface, which attracts the balloon.

An illustration showing a grey jumper labelled 'PhET' at the collar, densely populated with red positive charge symbols. Beside it is a yellow balloon, with many blue negative charge symbols, tethered by a string. To the far right, there's a patterned section displaying numerous red positive and blue negative charge symbols side by side. The negative charges from the balloon and the wall are repelling each other.

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.

A dramatic night-time scene with multiple bright lightning bolts striking through dark stormy clouds, illuminating the silhouette of a forested horizon.

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