TWI Frequently asked questions
by Malcolm Spicer
Eddy currents are electrical currents induced in metals by alternating magnetic fields.
An alternating current is passed through a coil:
The alternating current generates an alternating magnetic field:
The alternating magnetic field induces electrical currents called eddy currents in a conductor:
The eddy currents generate an opposing magnetic field which modifies the current in the coil:
A meter or display device is connected to the coil and any change in the intensity of the eddy currents will affect the current in the coil and so be shown on the meter or display device.
