How do eddy current brakes work?

An eddy current brake uses electromagnetic induction to slow or stop moving objects without physical contact or friction. When a conductive material moves past a magnetic field, circular electric currents called eddy currents are induced within it. These currents generate an opposing magnetic field that creates a drag force, converting the kinetic energy of the moving object into heat.

What we know

• A conductive surface moving past a stationary magnet develops circular electric currents known as eddy currents due to electromagnetic induction. [2, 3]
• According to Lenz's law, the circulating eddy currents create their own magnetic field that opposes the original magnetic field, causing a drag force on the moving conductor. [2, 3]
• The kinetic energy of the moving object is dissipated as heat generated by the current flowing through the electrical resistance of the conductor. [2, 3]
• Because eddy current brakes do not rely on friction surfaces, they experience no mechanical wear from brake shoes, though they cannot provide a holding force when the object is completely stationary. [2]

Where to go next

• the bigger pictureWhat are eddy currents?
• compared withHow do friction brakes compare to electromagnetic brakes?
• a case in pointWhere are eddy current brakes used in roller coasters and high-speed trains?
• how it workedHow does Faraday's law of induction govern electromagnetic braking?
• an unexpected connectionWhat is dynamic braking in locomotives?

Sources

• [1]eddy current brake (Wikidata Q2585557) · CC0 1.0
• [2]Eddy current brake · CC BY-SA 4.0
• [3]Eddy current · CC BY-SA 4.0
• [4]Auto belay · CC BY-SA 4.0
• [5]Dynamic braking · CC BY-SA 4.0