The national grid

• What is the national grid?

  A giant network of transformers and wires
• Where does most electricity in the UK come from?

  Power stations
• How do power stations generate electricity?

  By converting thermal energy into electrical energy
• What factors influence how much electricity power stations generate?

  Demand
• When does electricity demand generally peak?

  In the late afternoon and evening
• Why do power stations need spare capacity?

  To cope with surges in demand
• What is the equation for power?

  Power = Voltage × Current
• What happens when high current flows through a wire?

  It generates lots of heat due to resistance
• How do we minimize energy loss during transmission?

  By keeping the current low and voltage high
• What do we use to increase voltage before transmission?

  Step up transformers
• What voltage do step up transformers increase to?

  Around 400,000 volts
• What happens to the voltage before electricity reaches its destination?

  It is reduced by step down transformers
• What voltage do step down transformers lower the electricity to?

  Around 230 volts
• Why is it important to lower the voltage before use?

  High voltages are dangerous and can damage appliances
• What is the process of electricity distribution through the national grid?

  • Electricity generated in power stations
  • Step up transformers increase voltage to minimize energy loss
  • Electricity transmitted through wires and pylons
  • Step down transformers lower voltage for safe use