F = BIl

  • The equation “F = BIl” is called the motor effect formula. It is used to calculate the force experienced by a current-carrying wire placed in a magnetic field.

  • F stands for the force which is measured in newtons (N).

  • B represents the magnetic field strength, also known as magnetic flux density, measured in teslas (T).

  • I stands for the current flowing through the wire, measured in amperes, or amps (A).

  • l signifies the length of the wire that is within the magnetic field, which is measured in metres (m).

  • This equation shows that the force is directly proportional to the magnetic field strength, the current, and the wire length. This means that if any of these quantities increase, the force also increases.

  • If the current or the magnetic field is reversed, the direction of the force also reverses.

  • This principle is applied in a range of technology, including electric motors and loudspeakers which rely on forces produced by magnetic fields to function.

  • In a diagram, the directions of the field (B), current (I), and force (F) are all at right angles to each other. This is often represented by the Fleming’s left-hand rule.