Simple Explanation

Small electric currents that swirl in circles inside metal when it's near changing magnetic fields.

Concise Technical Definition

Circulating currents induced in conductors by time-varying magnetic fields, which oppose the change that created them.

Layman-Friendly Analogy

Like mini whirlpools in a river, eddy currents swirl inside metal when a magnetic field changes nearby.

Industry Usage Summary

Common in transformers, motors, and inductors; used in braking systems, metal detectors, and can cause unwanted heat or energy loss.

Engineering Shortcut

Eddy currents = resistive loops induced by dΦ/dt; they cause Joule heating and counteract magnetic field changes (Lenz's Law).

Full Technical Explanation

Eddy currents are loops of electrical current induced within conductors when they are exposed to a changing magnetic field, as described by Faraday’s Law of Induction. These currents circulate in closed loops perpendicular to the magnetic field and oppose the change that generated them (Lenz's Law). They can generate significant localized heating and energy loss in systems like electric motors, generators, and transformers. While often minimized using laminated cores or magnetic shielding, eddy currents are also intentionally used in applications such as induction heating, non-contact braking systems in trains and amusement rides, and flaw detection in materials.