Question

What is eddy current? Mention two applications of eddy current.

Answer 1

Eddy currents are the currents induced in a metallic plate when it is kept in a time varying magnetic field. Magnetic flux linked with the plate changes and so the induced current is set up. Eddy currents are sometimes so strong, that metallic plate become red hot.

Application:-

(1)-In induction furnace, the metal to be heated is placed in rapidly varying magnetic field produced by high frequency alternating current. Strong eddy currents are set up in the metal produce so much heat that the metal melts. This process is used in extracting a metal from its ore.The arrangement of heating the metal by means of strong induced current is called the induction furnace.

(2)-Induction motor, the eddy currents may be used to rotate the rotor. When a metallic cylinder(or rotor) is placed in a rotating magnetic field , eddy currents are produced in it. According to Lenz's law, these currents tends to reduce to relative motion between the cylinder and the field. The cylinder, therefore, begins to rotate in the direction in the field. This is the principle of induction motion.