Magnetic force (between parallel conductors)


In magnetostatics, the force of attraction or repulsion between two current-carrying wires is often called Ampère’s force law. The physical origin of this force is that each wire generates a magnetic field, as defined by the Biot–Savart law, and the other wire experiences a magnetic force as a consequence, as defined by the Lorentz force. The force per unit length between two straight parallel conductors is related to the direct currents carried by the wires and the distance that separates the wires.

Related formulas


FmMagnetic force per unit length (N/m)
μ0magnetic constant
I1Current of the wire 1 (A)
I2Current of the wire 2 (A)
rDistance between the wires (m)