What is static electricity, how can it be used and what is the connection between static electricity and electric currents?

Static electricity can be explained in terms of electrical charges. When electrical charges move we get an electric current.

• to explain why static electricity is dangerous in some situations and how precautions can be taken to ensure that the electrostatic charge
is discharged safely
• to explain how static electricity can be useful.

When certain insulating materials are rubbed against each other they become electrically charged. For example if you rub a balloon on your pullover it will stick to it.

Negatively charged electrons are rubbed off one material onto the other. The material that gains electrons becomes negatively charged. The material that loses electrons is left with an equal positive charge. Electrons are rubbed off the balloon so it becomes positive. The pullover gains electrons so it becomes negative. Remember: negative objects have gained electrons positive objects have lost electrons

When two electrically charged bodies are brought together they exert a force on each other.
Two bodies that carry the same type of charge repel. Two bodies that carry different types of charge attract.

Electrical charges can move easily through some substances, e.g. metals.
The rate of flow of electrical charge is called the current.

A charged body can be discharged by connecting it to earth with conductor. Charge then flows through the conductor.

Dangers and uses.
Static electricity can cause sparks. Static electricity wants to get to earth (because it is repelling itself) and, if it has enough energy, it might jump the gap in the air to get to earth as a spark.

Sparks can cause fires, even explosions. Before any kind of vehicle is refuelled it should be earthed to get rid of any static electricity. Sparks can also damage electrical equipment like integrated circuits. People who build or fix computers make sure they are earthed.

An anti-static wristband	The nozzle should earth the car before fuelling starts
A photocopier uses static electricity to make ink particles stick to where we want them to go.	Static electricity is used to remove dust particles from chimney smoke.

   
HT " The greater the charge on an isolated body the greater the potential difference between the body and earth. If the potential difference
becomes high enough a spark may jump across the gap between the body and any earthed conductor which is brought near it.

Electrostatic charges can be useful, for example in photocopiers and smoke precipitators and the basic operation of these devices.