Magnetic Forces on Current-Carrying Wires

Moving charge carriers within a conducting wire can experience a magnetic force if that wire is placed in an external magnetic field. If the wire carries a current, the charge carriers transmit a net force to the wire. For a straight wire segment of length L, this force is given by

where L is a vector with magnitude equal to the length of the wire segment and direction given by the direction of current flow in the wire. Magnetic forces on wires with arbitrary shape may be calculated by using the above formula with an infinitesimal length element. The net force on a current loop in a uniform magnetic field is zero.