GCSE Physics (AQA)

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Force from an Induced Current

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Magnetism and electromagnetism Induced potential, transformers and the National Grid

Force from an Induced Current

7:02 The Generator Effect
Spec 4.7.3.1
Previous The Generator Effect Next Factors Affecting an Induced Potential Difference
  • A generator effect occurs when a magnetic field cuts through a conductor in a circuit.
  • The generator effect induces a potential difference in a conductor, which can induce a current if connected to a circuit.
  • This effect can be achieved by moving the conductor through a field or moving a field over a conductor.
  • When a magnet is moved into a coil of wire, the field lines move across the coil, inducing a potential difference and causing a current to flow.
  • The induced current generates its own magnetic field around the conductor.
  • The magnetic field induced by the current in the coil will have a similar shape to that of the bar magnet.
  • Two separate magnetic fields overlap, causing the coil and magnet to experience a magnetic force.
  • Magnetic forces are non-contact forces caused by overlapping magnetic fields.
  • The overlapping fields cause the magnet to experience a force that pushes it away from the coil, and the coil experiences an equal and opposite force.
  • The generated magnetic field opposes the change causing it, making it harder to move the magnet.
  • The direction of the generated field is important for predicting the direction of the force.
  • A resistive force is necessary for the magnet to do work against it, transferring kinetic energy to electrical energy.
  • Energy cannot be created or destroyed, only transferred.
  • The magnet's kinetic energy is transferred to the coil as electrical energy, resulting in an electric current.
  • The generated field must always cause a resistive force to slow the magnet down and transfer kinetic energy.
  • If the generated field sped the magnet up, it would gain kinetic energy instead of transferring it to the coil.