How Transformers work

• Most of our electricity in the UK is generated at large power stations spread across the country.
• The electricity generated at these power stations needs to be passed through step up transformers which increase the voltage to around 400,000 volts to minimize energy losses as it is sent across the country in a network of wires and pylons.
• Once the electricity reaches its destination, it passes through a step down transformer which decreases the voltage to around 230 volts for safe use in our homes.
• The role of a transformer is to increase or decrease the voltage of electricity.
• A transformer consists of a grey chunk of iron called an iron core which connects the primary coil on the left to the secondary coil on the right.
• An alternating potential difference is applied across the primary coil of a transformer, causing a current to flow and generate a magnetic field around the coil.
• The alternating magnetic field in the primary coil of a transformer induces an alternating magnetic field in the iron core because iron is a magnetic material that can become magnetized if exposed to a magnetic field.
• The iron core's magnetic field induces a potential difference across the secondary coil of a transformer, which if part of a complete circuit, causes current to flow around that secondary coil.
• A transformer is effectively transferring the current from the primary coil over to the secondary coil, but instead of the electricity just conducting straight across, it uses these induced magnetic fields.
• The reason that we have to use all this weird magnetic stuff is because it allows us to change the size of the potential difference.
• In a step up transformer, if we put a 10 volt supply in, we'll get a 20 volt supply out because there are twice as many turns in the secondary coil as there are in the primary coil.
• In a step down transformer, if there are fewer turns on the secondary coil than on the primary coil, the voltage will be stepped down.