The Motor Effect and Fleming's Left-Hand Rule

When a current-carrying conductor is placed in a magnetic field, it experiences a force. This is called the motor effect and it is the principle behind electric motors. This lesson covers the motor effect, the equation $F = BIl$F=BIl, and Fleming's left-hand rule. It maps to AQA GCSE Combined Science Trilogy (8464) specification section 6.7.2 — The motor effect.

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The Motor Effect

When a wire carrying a current is placed in a magnetic field, the two magnetic fields interact and produce a force on the wire. This is called the motor effect.

Conditions for the Motor Effect

The force is greatest when:

• The wire is at right angles (90°) to the magnetic field.

The force is zero when:

• The wire is parallel to the magnetic field lines (0°).

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The Equation: $F = BIl$F=BIl

The force on a current-carrying conductor in a magnetic field is given by:

$F = B \times I \times l$F=B×I×l