Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday’s law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field.
When a changing magnetic flux is applied to a bulk piece of conducting material then circulating currents called eddy currents are induced in the material. Because the resistance of the bulk conductor is usually low, eddy currents often have large magnitudes and heat up the conductor.
1) These are circulating currents like eddies in water.
2) Experimental concept given by Focault hence also named as Focault current.
3) The production of eddy currents in a metallic block leads to the loss of electric energy in the form of heat.
4) By Lamination, slotting processes the resistance path for circulation of eddy current increases, resulting in to weakening them and also reducing losses causes by them.
Examples of Eddy Currents:
1) Metal plate: In absence of magnetic field: No damping
Consider a metal plate which is suspended freely with the help of thread. As there is no magnetic field the plate will keep on oscillating without damping.
2) Metal plate with slots: In presence of magnetic field: Damping reduced
When the plate oscillates the damping is reduced as there is lesser area. The eddy currents are less as a result damping is reduced. Eddy currents will oppose the motion of the plate and as they are reduced so there the damping is reduced.