In the UK, homes have a constant supply pressure of electricity at 230 volts, but the appliances that we use need different amounts of electricity at this same pressure to work.
For this reason, the electrical current needs to be measured, but, because the electrons that carry the electrical charge are so small, and because their movement is so fast, trying to measure them individually would be impossible. It could be likened to buying sugar by asking for the quantity to be counted individually by the grain. To avoid such a situation we buy sugar by weight.
Similarly, electrons are grouped together into a unit known as a Coulomb, with one Coulomb representing over six times a million, million, million electrons! Combining such a vast group of electrons into one unit makes it possible to measure how many Coulomb pass a certain point each second rather than the individual electron. This combination of the Coulomb and a measure of time brings us to Amperes (Amp). Therefore, when a Coulomb of charge moves past a point within a second, the strength of the electric current is one ampere, one AMP, or 1A.
Again if we use the principle of water pressure, it too can serve to illustrate the amperage or flow of electricity in this way; The rate at which water flows at a constant pressure could be measured by the amount that comes out of the pipe at any given time, but if the diameter of the pipe was increased and the same pressure maintained, the flow of water would also increase.
In electrical terms, if the pressure of 230 volts was to remain constant, the rate at which the electricity flows is increased to individual appliances by the size of cable feeding it. The cable supplying an electric cooker, for example, would be much larger than the cable supplying a table lamp.
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