The Discovery of Electricy and Magnetism and the Generation of Electricity.

In the early 19th century the following similarity between two charged particles and two magnets was observed:

• both created "forces" that could operate in a vacuum

• charge had a postive and negative component; magnets had a north and south pole force could then be either attractive or repulsive.
  

• both the magnetic force and the electrostatic force strength decreased as 1/R²

In 1820 Oersted did this experiment:

and discovered that an electric current creates a magnetic field

Similarly, a coil of wire with a current passing through it generates a magnetic field. This is known as an electromagnet or solenoid .

So now we know that a current can create a magnetic field. If a magnetic field can create a current then we have a means of generating electricity. Experiments showed that a magnetic just sitting next to a wire produced no current flow through that wire. However, if the magnet is moving a current is induced in the wire. The faster the magnet moves, the greater the induced current.

This is the principal behind simple electric generators in which a wire loop is rotated between to stationary magnetics. This produces a continuously varying voltage which in turn produces an alternating current .

Diagram of a simple electric generator:

	In this position there is no current flow but their is a large potential difference (a large voltage)
	In this position the Voltage is now zero and the current flow is at a maximum

To generate electricty then, all we really want to do is have some (mechanical) mechanism turn a crank that rotates a loop of wire between stationary magnets. The faster we can get this crank turned, the more current we can generate.

This is still the way that we generate electricity today which is the reason why electricity generators are large and weigh a lot. Copper wire is heavy and magnetic material is even heavier. You will never be able minitaurize the actual generation of electricity and voltage. This is the reason that your laptop battery weighs more than any of the other components in your computer. These days laptop batteries now have a new form factor to make laptops thinner but it means you can't replace the battery easily.