GCSE Physics (AQA)

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Potential Difference from an Alternator

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Magnetism and electromagnetism Induced potential, transformers and the National Grid

Potential Difference from an Alternator

8:04 Applying the Generator Effect
Spec 4.7.3.2
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  • The potential difference and current in an alternator change as it rotates.
  • An alternator converts kinetic energy into electrical energy by inducing a potential difference.
  • The coil in an alternator is rotated using a turbine or hand crank, causing it to spin in a magnetic field.
  • This rotation causes the sides of the conductor to cut through magnetic field lines, inducing a potential difference and current in a connected circuit.
  • The induced current is an alternating current (AC), where the potential difference and current periodically change direction.
  • The potential difference depends on the coil's motion and the speed at which it cuts the magnetic field lines.
  • When the coil is vertical and moving parallel to the field lines, no potential difference is induced.
  • As the coil moves down and cuts the field lines perpendicularly, the potential difference increases to a maximum.
  • The potential difference then decreases back to zero as the coil returns to a vertical position.
  • When the coil moves up in the opposite direction, the potential difference becomes negative due to the change in direction of motion.
  • The alternator setup causes the direction of the current in the connected circuit to change accordingly.
  • The potential difference can be increased by using more turns in the coil, wrapping the coil around an iron core, using stronger magnets, or rotating the coil faster.
  • Rotating the coil faster increases both the maximum potential difference and the frequency of the alternating potential difference.
  • The frequency of the alternating potential difference refers to how often its pattern repeats on a graph.
  • Rotating the coil faster results in higher peaks and less time between the peaks on the graph, indicating a higher frequency of alternation.

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