What principle does the concept of eddy currents rely on?

The concept of eddy currents relies on the principle of magnetic induction. Eddy currents are generated when a conductor experiences a changing magnetic field, which induces circulating loops of electric current within the conductor. This phenomenon is a direct result of Faraday's law of electromagnetic induction, which states that a changing magnetic field within a closed loop of wire induces an electromotive force (EMF) in the wire.

In practical terms, when an alternating magnetic field interacts with a conductive material, it causes free electrons in that material to move, creating currents that flow in closed loops, known as eddy currents. These currents can lead to energy loss through resistive heating but are also useful in various applications such as induction heating and non-destructive testing. The induced currents, their strength, and distribution depend on factors like the rate of change of the magnetic field, the material's conductivity, and the geometry of the conductor.

Understanding magnetic induction is crucial for anyone working with eddy current testing (ECT) or related techniques, as it underpins the operational principles that govern how these currents are generated and utilized.