# Electricity - Static Electricity

Electricity is a major topic covered in GCSE Physics. One aspect of electricity that students will learn about is static electricity - a stationary electric charge produced by the transfer of electrons between certain insulators as a result of friction. In this quiz we look at some examples of static electricity and at some of its effects.

Have you ever been 'zapped' as you get out of a car or touched metal shelving in a shop with carpeting on the floor? Have you ever rubbed a balloon on your clothing and stuck it to a wall? Have you ever watched lighning during a storm? If you have, then you have experienced static electricity in action!

Static electricity is a stationary electric charge, produced by friction acting on certain electrical insulators. As you rub an insulator, such as the soles of your shoes on the carpet or the balloon on your clothing, electrons are knocked off some of the atoms and are transferred from one to the other.

Since an insulator does not allow charge to move easily through it, the charge builds up on the surface. Although the charge cannot pass through the insulator, it can move around the surface and the whole of the surface becomes charged. If you are attached to a charged material, you also will become charged, which is why, when you touch a conductor such as a car door or metal shelf, the static electricity becomes current electricity and you receive an electric shock.

It affects many things in our daily lives and can be a major issue in the manufacture of small electrical devices, which are easily damaged by static electricity. Many computer manufacturers have electrically conductive flooring to ensure that static electricity is not produced when their workers are producing microchips. Computer repairers will also usually wear an anti-static bracelet that connects to the casing of the inside of a computer. This ensures that they are always at the same electrostatic potential as the computer as they know that an accidental discharge of static electricity (they call it an ESD - electrostatic discharge) could destroy the sensitive electronics.

When static electricity is generated, one insulator becomes negatively charged and the other becomes positively charged - the one that receives the electrons is negative. Oppositely charged objects attract one-another, but any charged object can attract small uncharged objects. This is why plastic materials and things like computer screens and TV screens attract so much dust.

Static electricity can be extremely dangerous in certain conditions - the most obvious is if you are hit by lightning. In factories producing finely ground materials, like flour for example, sparks of static electricity have caused deadly explosions. As the fine particles are pumped around a factory, they rub against each other and this friction makes them statically charged. The charge spreads out on the surface of the pipes and when it builds up to the point where it can spark, if there are a lot of the fine particles in the air, they could ignite - you should know from chemistry that powdered materials burn much faster than lumps. The same applies to pumping inflammable liquids - high concentrations of vapour can be ignited by a spark. This is prevented by connecting the pipes to the ground through a conducting wire, and also by reducing the amount of dust or vapour in the air during the operation.

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1. If one positively charged material and one negatively charged material are brought in close proximity to one another, what force do they exert on each other?
Two materials which have different types of electrical charge will always attract one another
2. Which material from the list below allows an electrical current to pass through it easily?
Metals allow electrical currents to pass through them easily due to the high number of free electrons within the material
3. If two positively charged materials are brought in close proximity to one another, what force do they exert on each other?
Repulsion works with positive charges the same as it does with negative charges
4. What type of charge does the material losing electrons have?
Since the object was electrically neutral beforehand, losing negative charge will mean that it ends up with a positive charge
5. If two negatively charged materials are brought in close proximity to one another, what force do they exert on each other?
Charges of the same type repel
6. If two charged materials are brought close together, what do they exert on each other?
We talk of this as being an electrostatic force
7. What type of charge does the material gaining electrons have?
A material that gains electrons will always become negatively charged as the electrons themselves are negatively charged
8. If two polystyrene rods are rubbed with a duster and gain electrons, how will the rods react to one another when they are brought close together?
They both gain electrons so must be negatively charged - two objects with the same electrosatatic charge will repel each other
9. What is 'rubbed' off one material and onto the other?
These collect on the surface of the negatively charged object
10. What do certain insulating materials become when they are rubbed against each other?
One becomes positively charged and the other becomes negatively charged by the same amount