Power supplies and energy transfers Typeit

Electricity is another word for the flow of charged particles through a component. The rate at which these charges travel is called the , while the energy transferred per unit charge is called the .
Electricity is delivered to homes and businesses via the National Grid, known as mains electricity. This is delivered at V and Hz in the UK.
A mains plug has three core cables. The cable carries the electricity from the National Grid to an appliance, and is always dangerous to touch. The cable completes the circuit, carrying electricity back to the National Grid. The cable is a safety feature, and only ever carries electricity when there is a fault in the appliance or other cables.
The National Grid contains many transformers, which change the properties of the electricity carried for efficiency and safety. transformers are situated between power stations and the series of cables which make the National Grid, to decrease the amount of energy wasted during transfer. transformers deliver electricity to homes and businesses, and make the voltage a suitable level for domestic appliances to work safely and efficiently.

A current flows when there is a across a conductor in a circuit. When a current flows, move within the conductor and do work against the resistance of the material through collisions. Some of this work done can be harnessed as useful energy and some is as heat. In power cables the losses through heat are minimised by the voltage which results in a low current or flow of electrons. A lower flow of electrons means collisions and less energy is dissipated in the form of heat. Another way of reducing unwanted energy transfer through heat is by using wires. Sometimes producing heat is a waste of energy but is beneficial, such as in electric heaters. Electric heating elements have high .