(صورة توضيحية فقط)
Eddy currents are loops of electrical current induced within bulk conductors by a changing magnetic field, in accordance with Faraday’s law. They flow in closed loops in planes perpendicular to the magnetic field. Following Lenz’s law, these currents create their own magnetic field that opposes the change in the external flux, causing a repulsive or drag force and resistive heating.
When a solid metallic conductor moves through a magnetic field or is exposed to a time-varying field, the free electrons within it experience a Lorentz force, causing them to circulate. These swirling currents are called eddy currents. Their magnitude is proportional to the magnetic field strength, the area of the loops, and the rate of flux change, and inversely proportional to the material’s resistivity. The power dissipated as heat ([latex]P = I^2R[/latex]) can be substantial, an effect harnessed in induction heating.
In many applications, such as transformer and motor cores, eddy currents are undesirable as they represent a significant energy loss (core loss). To mitigate this, the cores are constructed from thin, laminated sheets of a ferromagnetic material like silicon steel, with each sheet electrically insulated from the next. This lamination breaks up the large conductive paths, forcing the eddy currents into much smaller, higher-resistance loops, thereby drastically reducing the energy lost to heat.
Eddy Currents (Foucault’s Currents)
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