National Grid

• Fossil fuel and nuclear power stations work by generating thermal energy. This is used to turn water into steam which can then rise and turn turbines. The kinetic energy of the moving turbines can be converted to electrical energy, which is finally sent out across the national grid.
• Electricity demand varies during the day and generally peak late in the afternoon
• The formula for electric power is power=voltage×current
• When transmitting electricity, a high current generates lots of wasted heat. High currents cause the wire to heat up, meaning that energy is lost as heat to the surroundings. 
• Step-up transformers are used to increase the voltage and decrease the current
• Step-down transformers are used to decrease the voltage and increase the current
• Electric power is generated at a power station. Step up transformers increase the voltage and decrease the current. The electric power is transmitted via the national grid at low current which minimises power loss.  Step down transformers decrease the voltage and increase the current near our homes. Electric power is wired into our homes at a voltage that is relatively safe to use - 230V
• The National Grid distributes electricity across the country. The National Grid connects power stations to homes, workplaces and public buildings all around the country. The electricity can be produced by a conventional power station turning a generator.
• In the UK, the mains electrical supply is generated at a frequency of 50 Hertz (Hz) and is delivered to houses at 230 Volts (V).
• When charge always flows around a circuit in the same direction, we call it direct current
•  Alternating current is caused by an alternating potential difference.
• Direct current is supplied by cells and batteries
• The role of an oscilloscope is to display how voltage changes with time
• An alternating current regularly changes direction.
• Wires are made of copper and coated in a layer of insulating plastic
• Touching the live wire will result in an electric shock.
• Which wire prevents the electrical casing from becoming live?

  Earth wire
• Which wire supplies the current to the appliance?

  Live wire
• Which wire completes the circuit, allowing current to flow?

  Neutral wire
• What is the voltage of the neutral wire?

  0V
• What is the voltage between the live and neutral wire?

  230V
• Which two wires have the same voltage? 

  Earth and neutral - they both have 0V
• What colour is the earth wire?

  yellow and green
• What colour is the live wire?

  brown
• What colour is the neutral wire?

  blue