Calculating Magnetic Force on a Current-Carrying Conductor
Higher Tier Only
- The size of the force acting on a current-carrying wire in a magnetic field can be calculated using the equation:
F = BIL
- Where:
- F = force acting on current-carrying wire in newtons (N)
- B = magnetic flux density (which is the strength of the magnetic field) in tesla (N/A m)
- I = current flowing through the conductor in amps (A)
- L = length of the conductor that is in the magnetic field in metres (m)
Force on a current carrying conductor (directed into the page)
Worked example
A 5 cm length of wire is at 90o to the direction of an external magnetic field. When current of 1.5 A flows through the wire it experiences a force of 0.06 N from the motor effect.Calculate the magnetic flux density of the magnet.
N/A m = T
Exam Tip
You will only be expected to calculate the force when the wire is perpendicular to the field, so you won't have to worry about angles.
