what is eddy current?

Eddy currents (also called Foucault currents ) are electric currents  induced within conductors by a changing magnetic field in the conductor.

When a conductor moves through an inhomogeneous field generated by a source, electromotive forces (EMFs) can be generated around loops within the conductor. These EMFs acting on the resistivity of the material generate a current around the loop, in accordance with Faraday''s law of induction. These currents dissipate energy, and create a magnetic field that tends to oppose changes in the current- they have inductance.

Eddy currents generate resistive losses that transform some forms of energy, such as kinetic energy, into heat. This Joule heating reduces efficiency of iron-core transformers and electric motors and other devices that use changing magnetic fields. Eddy currents are minimized in these devices by selecting magnetic core materials that have low electrical conductivity (e.g., ferrites) or by using thin sheets of magnetic material, known as laminations .

if u have any doubts.. plz refer Electrical technology books

the current induced in the conductor due change in magnetic field is called eddy current.we study more about this in electro magnetic laws.