What is electricity?
Electricity is a flow of electrons from one point to another along a conduit. The organised flow of electrons is called a current and when delivered at the right voltage (pressure) it powers our lights and appliances.
Matter is made of atoms that have a positively charged nucleus orbited by negatively charged electrons. In some matter, particularly metals like copper, the outer orbiting electrons can float ‘free’ in the metal around positive ions. This availability of free electrons means these substances are good conductors.
Electrons have a negative charge. Like charges repel and electrons can be organised to flow by creating a difference in the charged ends of a circuit.
Often it is the movement that does the work for our use. Electrons can move in one direction (direct current, or 'DC' systems, like batteries) or back and forward many times a second (alternating current, or 'AC' like mains power). Resistance to this movement through the introduction of a filament/light bulb (transferring to heat and light energy) or motor (transfer to kinetic energy) is how we see electricity working in our homes.
In Western Australia we have AC delivered to our homes at 240 volts.
Volts, current and kilowatt hours
Volts, current (amperes) and resistance are the key elements to understand electricity.
The rate that electrons flow through a conductor is measured in amps. A single ampere is the measure of many millions of billions of electrons moving per second through a circuit (6.25 x 10^18). Amps are positively related to voltage. Where amperes is the flow of electricity, the volts are commonly referred to as the pressure, or the force in which electrons move through the circuit. Electrons are negatively charged, and like poles of magnet they are motivated to move away from each other.
When placed under pressure in a battery oppositional force pushes electrons to move with force. AC electricity results in electrons moving back and forth many times a second which is created by spinning a magnet around a conductor, attracting and repelling electrons very quickly. Resistance is the work we ask the electrons to do. Often resistance transfers the electricity to heat (like in a light) or movement (in a motor). In some appliances both of these things happen – consider a toaster, heating element to cook your bread and a mechanisms to pop it up when it’s done.
In summary, the voltage is equivalent to the water pressure, the current is equivalent to the flow rate, and the resistance is like the pipe size.
If you have ever looked closely at your electricity bill you will notice that that your consumption of electricity is measure in kilowatt hours (KWh). Watts is the power your household used – effectively the voltage multiplied by the amperes – over your billing period. For example, if you only ran one 100 Watt light bulb for 10 hours every day for a 30 day month, your usage would be (100W x 10 hours x 30 days) 30,000 Watt hours, or 30 KWh.
How does electricity make things work? Heat and movement.
Energy has many forms. Electricity, or electrical energy, is the flow of electrons. To make things work, we introduce resistance into a circuit of electrons flowing and make these electrons pass on this energy. This transformation is work. It can be transformed into heat and light for our homes, and it can be transformed into kinetic energy to power a motor. These are the common types of energy we use in our home.