Power is a measure of the rate at which energy is used. The unit of power is watt (W).
power = voltage x current
Electrical consumption is the amount of energy that has been used. The unit is kilowatt-hour (kWh).
energy used = power x time
The cost of use of an electrical appliance depends on the energy it uses. It is calculated as follows, in pence (p):
cost = energy x (cost per kilowatt hour)
You may have seen the electricity meter in your house. There are two shown in the diagrams below. One is an old type metre and one is a new digital metre. Can you tell which one is digital?
There are two rates of electricity; a day and a night one. Using electricity at night is cheaper, because it is still produced (as power stations need to work non-stop), but there is less consumption. Showers or cookers use a lot of energy, whereas a light bulb uses much less.
Most electricity in the UK is produced by burning coal. However, burning coal and other fossil fuels (natural gas and oil) produces carbon dioxide. This is a greenhouse gas and contributes to global warming. Sulfur dioxide is also produced and that dissolves in rainwater forming acid rain.
To avoid further environmental pollution, some power stations now use biomass fuels, such as wood, straw or manure (animal dung); however, carbon dioxide is still produced. Nuclear power stations do not pollute the environment, because nothing is being burnt there. Instead, uranium atoms are allowed to split, releasing a lot of energy as heat. If this reaction is not carefully controlled, there could be a nuclear explosion and that is a BIG disadvantage.
We will now answer some questions on the cost of electricity.