Explanation

Describe the physical quantity of magnetic properties of current carrying coils or microscopic particles. The magnetic moment of the plane current carrying coil is defined as m=iSe. In the formula, i is the current intensity; S is the coil area; E is the unit vector in a right-hand spiral relationship with the direction of the current. In a uniform external magnetic field, the resultant force on the plane current carrying coil is zero but the torque is not zero. This torque makes the magnetic moment m of the coil turn to the same direction as the direction of the external magnetic field B; In a uniformly radially distributed external magnetic field, the planar current carrying coil is deflected by torque. The working principle of many motors and electrical instruments is based on this.

Classification