GCSE Physics (AQA)

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The Motor Effect

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Magnetism and electromagnetism The motor effect

The Motor Effect

4:27 The Motor Effect
Spec 4.7.2.2
Previous Electric Motors Next Calculating the Force on a Wire
  • The motor effect occurs when a magnet and a current-carrying wire exert a force on each other.
  • A magnetic field exists between two magnetic poles.
  • Normally, this field affects other magnetic poles or certain magnetic metals.
  • A wire carrying an electric current in the field will experience a force, even if made from non-magnetic metal like copper.
  • The force causes the wire to move perpendicular to the field, not towards the poles.
  • Newton's third law states that magnets will experience an equal and opposite force.
  • A current-carrying wire produces a magnetic field, gaining a circular magnetic field.
  • When placed near a magnet, the wire's field interacts with the magnet's field.
  • The interaction results in a complex pattern where fields overlap and exert forces.
  • Field lines indicate the direction of magnetic force; the force on the wire is up or down, not left or right.
  • The force causes the wire and magnets to move apart, allowing fields to return to original patterns.
  • For exams, recognize when a current-carrying wire will experience a force.
  • 3D diagrams simplify to show only the current in the wire and the magnetic field.
  • Diagrams use dot and cross notation to represent field direction (dot = out of page, cross = into page).
  • In exams, interpret diagrams to identify if a motor effect would occur.

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