Electricity is an important part of our lives. At a basic level we need it to keep warm, to prepare food and to see in the dark, but it’s also essential for less vital activities, such as watching TV, playing computer games and charging our phones.
So what is electricity, exactly, and how does it work?
Electricity is a type of energy that can accumulate in one place or flow across from place to place. Electricity that accumulates is static electricity, while electricity that keeps moving is current electricity.
Electricity exists all around us, in nature (lightning, for instance) and in our everyday lives (think about the shock you sometimes get when you touch a metal object – that’s electricity). Electricity has always existed, but it wasn’t until the early 19th century that scientists learned how to harness its power.
Electricity provides power that we use every day, to light our homes and streets, to keep our food cool or heat it up, and to provide us with entertainment and communications.
The way we use electricity is changing all the time. More and more homes, businesses and communities are working towards generating their own renewable electric power. At the same time our dependence on electricity is growing, with the development of mobile phones, the internet and even electric cars.
Here’s the science. Everything in life is made up of microscopic atoms. Within an atom there are protons which have a positive charge, neutrons which have no charge, and electrons which are not part of the nucleus (centre) of the atom, but which move around in orbits outside the nucleus. When electrons flow together electricity is created.
If you walk across a nylon carpet or rub a balloon on your clothing, you can create static electricity. The movement of rubbing the balloon or brushing your feet against the carpet creates energy, and this builds up without flowing anywhere, so it becomes static electricity. That’s why you can get a shock when you next touch a door handle after walking on the carpet, or why your hair is drawn towards the balloon.
Generating electricity to use in our homes and businesses requires a fuel source, such as coal or oil, or a renewable source such as the sun or wind. The fuel is used to power a turbine which spins magnets surrounded by copper wire. This encourages electrons to flow, generating electricity, which is stored and then transported to where it’s needed (e.g. your home).
As electrons move from one place to another, they carry electricity with them, creating current electricity (also known as an electric current). It’s these currents that power all the electrical appliances we use, from tablets to tumble dryers.
Static electricity is stuck in one place and doesn’t power anything, but it has the potential to become current electricity. The electricity in a battery, for example, is potential energy. When it’s still in its packaging it’s not doing anything, but once you put it in an item like a shaver or radio it starts releasing its power, creating an electric current.
Electricity can’t just flow randomly out into the atmosphere. It needs to flow along a closed circuit. In most appliances this circuit is created by linking components together with wires.
Remember the example we used for static electricity, when you rub your feet along a nylon carpet? Well, when you then touch something – a door handle, a friend’s shoulder, a pet’s ear – you’ve completed the circuit the energy needs. The electrons can start moving, and you get a small electric shock.
When you switch on a light or an appliance, the switch creates a link between wires or other components to complete the circuit so the electricity can flow around it. Once the switch is turned off, the circuit is no longer complete and the energy stops flowing. That’s why some switches are known as circuit breakers.
Sometimes the circuit is invisible. For example, in the case of lightning, charged ions in the air combine to create a link between a storm cloud and the Earth, along which the lightning can travel.
Electricity is measured in several ways. You can measure its voltage, current, power or energy.
Voltage is the force that moves electricity. The greater the voltage, the more electricity it can move through an appliance – so a 12 volt battery (the size you get in a car) will produce more current than a 1.5 volt battery in a TV remote.
Current is the flow of electrons through the circuit (powered by the voltage), and it’s measured in amperes (amps).
Power is voltage and current multiplied together. Electric power is measured in watts, so watts = volts x amps. If you have a 60 watt bulb powered by a 1.5 volt battery, the amount of current flowing is 60/1.5 = 40 amps.
A 60 watt light bulb is a bulb that needs 60 watts of power in order to work. Most electrical appliances (like this hypothetical light bulb) are marked with the number of watts they need in order to work.
kW stands for kilowatt. A kilowatt is simply 1,000 watts. So, for example, a 10,000 watt electric shower is exactly the same as a 10 kilowatt shower.
Energy is most commonly measured in watt hours (Wh) or kilowatt hours (kWh) – i.e. the number of hours an appliance has been working at a given wattage. Our 60 watt light bulb left on for one hour will use 60 watt hours (Wh) of electricity.
A kilowatt hour is a thousand watt hours. So a 1,000 watt drill needs 1,000 watts (1 kW) of power to make it work, and uses 1 kWh of energy in an hour.
That’s why, if you leave a TV or computer on standby, it is still using power and creating a kWh cost on your energy bill.
Electricity companies usually charge customers per kilowatt hour (kWh), and sometimes call these ‘units’.
Electricity moves around circuits as either alternating current (AC) or direct current (DC).
Direct current is when the electrons simply go round and round a loop, always in the same direction. Most small items or toys would use electricity like this.
In alternating current, the electrons keep reversing direction, whizzing backwards and forwards about 50 times every second, as if they’re running on the spot. This is usually used to power bigger appliances like washing machines and electric hobs.
External sources: http://www.explainthatstuff.com/electricity.html