Current

CURRENT ELECTRICITY

We are reasonably familiar with some aspects of hooking up electrical circuits as most of us have connected wires, batteries and light bulbs sometime at school but maybe it didnít entirely gel as logical and sensible.

Words associated with electricity include

circuits, resistance, conductors, current, voltage, power, cells, batteries, ohms, voltmeters, ammeters, .................... .

These seem confusing and at times, interchangeable.


Let us go over real basics.

To make "something" (refrigerator, light, computer, radio controlled car, sewing machine......) turn on we need

an appropriate source of electricity,
metal wires insulated with plastic,
a switch
and the thing.

We connect them in a distinct sequence for the thing to work.

The source is a source of energy.

- In the case of a 1.5V AA cell, it has a limited life then is unusable so we throw it away.

- In the case of the 240V Hydro provided electricity, it is far closer to limitless as an energy source. (The energy can be traced back to Gravitational potential energy of water.) The limitations are - what you can afford to buy, or, how much Tasmanians are prepared to allow to be created.

The energy is transferred to the globe or CD player where it changes to light or heat or motion or sound - all forms of energy. Because the connecting wires are extremely good conductors of electricity, very little energy is lost as heat in them. The switch merely allows or stops the transfer of energy.

But why is it necessary to have two wires? Surely the transfer can take place with only one wire? The answer lies in the method of transfer - the motion of electrons from high potential energy in the source to low potential energy in the source. One wire carries electrons to the globe or CD player from the source, the other returns them to the source whereupon they are boosted back up to continue their circulation.

In any material, especially...