GCSE Physics (AQA)

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Magnetic Field Around a Wire

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Magnetism and electromagnetism The motor effect

Magnetic Field Around a Wire

4:18 Induced Magnetism
Spec 4.7.2.1
Previous Magnetic Field Around the Earth Next Right Hand Grip Rule
  • All wires produce a magnetic field when conducting an electric current.
  • No magnetic field is present when a charger is switched off and no current flows.
  • A compass can detect a magnetic field by aligning to it instead of the earth's magnetic field.
  • When a charger is switched on, the compass needle points towards the cable, indicating a magnetic field.
  • The magnetic field around a wire is circular, as shown by iron filings.
  • Field lines indicate the direction of force on a magnetic object.
  • Iron filings align along magnetic field lines, forming concentric circles around a wire.
  • The strength of the magnetic field depends on the distance from the wire and the current amount.
  • Field strength is judged by the proximity of field lines; closer lines indicate a stronger field.
  • Increasing current results in more and closer field lines, indicating greater field strength.
  • The direction of the current determines the magnetic field's direction.
  • The field direction affects the force on magnetic poles, with opposite forces on north and south poles.
  • Reversing the current reverses the magnetic field direction.

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