National Grid

• What is the national grid?


  It is a giant network of transformers and wires that distributes electricity across the country.
• From what sources is electricity generated in the UK?


  Electricity is generated from a range of different sources, primarily power stations.
• How do power stations generate electricity?


  They generate heat and convert that thermal energy into electrical energy.
• What factors influence how much electricity power stations generate?


  The amount of electricity generated depends on the demand for electricity.
• When does electricity demand typically peak in the UK?


  Electricity demand peaks in the late afternoon and evening.
• Why do power stations need to have spare capacity?


  To cope with surges in electricity demand.
• What happens when high current flows through a wire?


  It generates lots of heat due to the resistance in the wire.
• What is the equation for power in electrical systems?


  Power is equal to voltage times current.
• How can we achieve high power in electrical transmission?

  By using high voltage and low current.
• Why do we need to keep the current low in the national grid?


  To minimize energy loss due to heat generated by resistance in the wire.
• What do step-up transformers do in the national grid?

  They increase the voltage to around 400,000 volts
• What is the role of wires in the national grid?


  They transmit electricity across the country between pylons.
• What do step-down transformers do before electricity reaches its destination?


  They lower the voltage to around 230 volts.
• Why is it important to lower the voltage before electricity is used in homes?

  High voltages are dangerous and could damage appliances.
• What is the process of electricity transmission in the national grid?

  • Electricity is generated in power stations.
  • Step-up transformers increase voltage and decreases current to minimize energy loss (because lower current causes less energy loss due to the high resistance of the cables)
  • Electricity is transmitted through wires across the country.
  • Step-down transformers lower voltage and increases current to make it safe for use in homes.