Question

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

Answer 1

Hint: Eddy currents are currents induced in the body of the conductor when they are subjected to changing magnetic flux. They are also called as Foucalts currents.

Complete step by step answer
Some of the most common applications of eddy current are
-Magnetic braking in trains: Strong electromagnets are located above the rails and when they get activated as the rails oppose the motion eddy currents are induced.
-Electric power meters: Eddy currents cause the rotation of shiny metal discs in the electric power meter. Electric currents are induced in the disc by magnetic fields produced by alternating varying currents in a coil.
-Induction furnace: Induction furnace is used to prepare alloys and produce high temperatures. When a high frequency sinusoidal current is passed through the metals, metals melt due to the high temperature produced by the eddy current.

Additional information
Eddy currents are actually undesirable because they heat up the core and dissipate electrical energy in the form of heat. They can be minimised using laminations of metal to make a metal core.
Consider a metallic plate in the absence of magnetic field without damping and if we are freely suspending it with help of a thread it will keep on oscillation without damping. This is another application of eddy current.

Note
Eddy current always has the tendency to oppose the relative motion. Since they oppose the relative motion they cause damping. They are the same eddies in the water because as the movement continues and current also keeps changing their direction depending on the change in flux.