Energy, Power and the National Grid

• What is the relationship between energy charge and work done?

  Energy charge flows, work is done
• How is energy transferred in a kettle?

  Energy is transferred electrically to thermal energy store
• How is energy transferred in a fan's motor?

  Energy is transferred electrically to kinetic energy store
• What is the formula for energy transferred in terms of charge flow and potential difference?

  E = QV
• What factors determine the amount of energy an appliance transfers?

  Appliance's power and duration of use
• What does power represent in terms of energy transfer?

  Energy transferred per second
• What is the maximum safe power an appliance can operate at called?

  Power rating
• What is the formula for power in terms of potential difference and current?

  P = VI
• What is the formula for energy transferred in terms of power and time?

  E = Pt
• What is the formula for power in terms of current and resistance?

  P = I²R
• What is the National Grid?

  A system of cables and transformers
• How is electrical power transferred in the National Grid?

  At high potential difference and low current
• What does a step-up transformer do in the National Grid?

  Increases potential difference
• What does a step-down transformer do in the National Grid?

  Decreases potential difference
• Why is transferring power at high current inefficient?

  It heats up wires and wastes energy
• What are the key components of the National Grid?

  • Cables
  • Transformers
  • Power stations
  • Consumers
• What are the advantages of transferring electrical power at high potential difference?

  • More efficient energy transfer
  • Reduces energy loss as heat
  • Allows for long-distance transmission
• What are the formulas related to power and energy transfer?

  1. E = QV
  2. P = VI
  3. E = Pt
  4. P = I²R