Electricity generation - magnetic process:

Above - Magnetic field on a bar magnet - iron filings are used so that we can see the invisible field.

Fortunately we do not have to rely on batteries for our major electricity needs. If we did we would need special rooms in our homes just to house the huge and expensive batteries necessary to provide all the electricity we need. Also batteries deteriorate as the chemicals weaken with use.

We owe our modern electricity supplies and modern electrical machinery (motors and generators) to a brilliant English inventor of the early 1800s, Michael Faraday. Ignoring the developments in chemistry which Count Volta had been making a few years earlier, Faraday concentrated on the science of matter and energy. He believed electricity could be produced more efficiently by an entirely different method.

Since around 600BC, scholars have been fascinated by the magnetic properties of minerals such as amber which, when rubbed, can pick up small objects made of certain materials. The ancient Greeks called amber “elektron” which is the name from which the words electron and electricity are derived.

From this it was known that electricity produced magnetism. Surely, Faraday reasoned, magnetism must also be able to produce electricity. In 1831 Faraday, experimenting with magnets, proved that by spinning a copper disc between the poles of a horseshoe magnet, electrons could be greatly activated within the magnetic field. In other words, the combination of the copper metal conductor, plus magnetism, plus mechanical movement, generated electricity. The device used for generating electricity was called the dynamo. This dynamo and the principle involved is the basis for the electricity generators used in our modern power stations.

Today’s giant generators of electricity (alternators) are little more than sophisticated versions of the crude dynamo which Faraday used to generate a feeble electrical current. However, Faraday’s copper disc has been replaced by wire coils and powerful electro magnets have taken over from the simple horse-shoe magnet.

For more information about Faraday and magnetism, go to:
http://en.wikipedia.org/wiki/Michael_Faraday
http://en.wikipedia.org/wiki/Magnetism

To enlarge diagram - click here.

In a typical modern generator, the electro-magnet (rotor) is forced to spin inside banks of coiled wire conductors encased in a cylindrical iron shell (stator) – please refer to the above diagram. The rotor is spun by steam turbines. These steam turbines have turning blades and power generators, which produce electricity.
(See figures above and below).

Above - A diagram demonstrating how steam energy is converted into mechanical energy thus turning the fans in the turbine and thus turning the generator to produce electricit.
Source: Western Power’s World of Energy.

Broadly there are two types of electric current. One is called direct current or DC (a continuous flow of electricity) and the other is called an alternating current or AC. Batteries and dynamos produce DC, alternators at modern power stations produce AC. With AC, current flow reverses its direction in an alternating action. This has several technical advantages including the ease of increasing (stepping up) or decreasing (stepping down) voltages and current through transformers. There are no DC transformers.

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