The mains is the system that electricity is passed from the power stations through cables into to your house to power all the modern necessities you currently own. The mains doesn't just provide for homes but for every building with electricity. All the power stations are connected to form the national grid which is in control of all the electricity, how much is supplied, where it goes and how it is produced.
Alternating current = current that rapidly and constantly changes direction.
Circuit = a loop that electricity goes around.
Demand = the need for something.
Direct current = a current that runs in one continuous loop.
Efficiency = how well something uses the electricity it has been supplied.
Magnetic field = areas around that attract or repel metallic objects.
Mains electricity = the electricity supplied from power stations to your home or work.
National grid = the combined power stations and mains electricity hub.
Power station = a place that produces electricity.
Supply = how much electricity is being produced.
Transformer = something that alters the voltage of an alternating current.
Voltage = an expression of potential difference between two points on an electrical current.
From Station to Sitting room
Electricity starts of by being generated in a power station and travel through to a step up transformer. This increases the voltage so they travel along the cables more efficiently with less heat loss. The Electricity then travel along cables whether they be over ground on pylons or underground through pipes to the step down transformer. This decreases the voltage so it will be safe to use. This may be decreased once for factories and other industrial units. It may then be stepped down a second time to a level safe for domestic use.
Transformers change the potential difference (Voltage) of a current but only when there is an alternating current (A.C). Step up transformers increase the voltage and they have more turns on the secondary coil compared to the primary coil. The Step down transformer decreases the voltage and there are more coils on the primary coil than on the secondary coil. The transformer works by something called electromagnetic induction which is covered in the magnetism section. The primary coil produces a magnetic field that stays within the metal core. This means it nearly all of it passes through the secondary coil and hardly any is lost. As the mains has an alternating current which passes through the primary coil the magnetic field is constantly changing directions and this is felt by the secondary coil.
The relative number of turns on the secondary coil compared to the primary coils alters whether the voltage increases or decreases. If a direct current were to be supplied nothing would happen on the secondary coils although the magnetic field will still work.
Overground or Underground
There are two ways of running cables between the different stations in the mains system. Here are the advantages and disadvantages:
Supply and Demand
The national grid (all the different power stations combined) needs to provide enough electricity to meet the needs of the people trying to access the electricity. In order to keep up with demand the national grid will need to expand or the demand will surpass the supply. Demand can be reduced by consumers (people) using more energy efficient devices, these are devices that use less electricity for the same amount of output.
To the right of this is a labelled plug and this has been specially designed to work with the mains. Find out about what the different components in the plug:
Fuse = the wire inside melts when there is a surge in electricity to prevent damage to the device.
Earth Wire = All electricity wants to travel back to earth which is why lightning hits people because it wants to travel the shortest distance back to earth. Most electronic devices have a metal case and the earth wire creates a safe way for the electricity to travel back to earth.
Live Wire = This is the wire that the electric current passes along into and out of the device.
Neutral wire = Is used to complete the circuit
Plastic Case = This is an insulator which means that the current doesn't pass from the wires into you.
Brass pickups = Brass is the most efficient way of passing electricity from the mains into the plug.
This topic is covered by the Code Ph.03. and there are resources available in the THS store for this topic. Student worksheets are free and we have a range of quality lessons available for purchase, these include lesson plans, activity's and presentations for each lesson.