GCSE Physics (AQA)

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Efficiency of the National Grid

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Electricity Energy transfers

Efficiency of the National Grid

2:27 The National Grid
Spec 4.2.4.3
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  • All wires and cables have a small amount of resistance.
  • Resistors have a larger resistance compared to wires due to a smaller concentration of ions.
  • Charge carriers lose energy as resistance causes wires to heat up, resulting in energy loss as heat.
  • Energy loss is due to collisions between charge carriers and ions in the conductor.
  • Wires are made with low resistance to reduce heat loss, but resistance cannot be entirely removed.
  • Power output of a component is given by current multiplied by potential difference.
  • Larger currents result in more energy lost to resistance.
  • Current is transported by delocalized electrons moving in the same direction through the wire.
  • Power in terms of resistance is given by P = i��R.
  • Larger currents cause faster electron movement, more collisions with ions, and more energy transfer, leading to more heat loss.
  • Understanding higher currents causing larger power losses is not required in detail for exams, but applying power losses to the equation is necessary.
  • Large energy losses occur when transporting electricity from power stations to homes due to long distances and low resistance wires.
  • The national grid uses transformers to transport electricity at as low a current as possible.
  • Transformers change the potential difference and current of an alternating current.
  • Electricity is transported at a large potential difference and small current to reduce energy losses, as lower current means less energy loss to resistance.

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