Eddy Current

Eddy current is a current that forms in a conductor when it's exposed to a changing magnetic field.  This occurs due to electromagnetic induction.  When a conductor, such as a metal plate or wire, is placed in a varying magnetic field, it generates circulating currents within itself.  These currents create their own magnetic fields, which oppose the original change in magnetic flux that induced them.  Eddy currents are commonly encountered in applications such as electromagnetic braking, metal detection, and electromagnetic induction heating.  They can also cause energy loss and heating in electrical devices, so they're often minimized or controlled in engineering designs.

Methods to Mitigate or Control Eddy Currents

Using Magnetic Shielding  -  Surrounding the conductor with a material that conducts magnetic flux more effectively than the surrounding air or material can help direct the magnetic field away from the conductor, reducing the induction of eddy currents.  This technique is commonly used in transformers and other electromagnetic devices.
Laminating  -  For conductive materials like metal plates or cores, laminating involves dividing the material into thin layers separated by insulating layers.  This reduces the size of the circulating currents since they have less volume of conductor to flow through.  Transformers and the cores of some motors use laminated cores to minimize eddy currents.
Using Non-Conductive Materials  -  In applications where eddy currents are undesirable, using non-conductive materials such as plastics or ceramics instead of conductive metals can prevent the formation of eddy currents altogether.
Eddy Current Brakes  -  In certain applications like trains or roller coasters, eddy currents can be intentionally induced in conductive materials to create resistance and slow down motion.  These are known as eddy current brakes.  In such cases, the eddy currents are not necessarily stopped but are rather utilized for a specific purpose.
Eddy Current Probes  -  In non-destructive testing, eddy current probes can be used to detect flaws or defects in conductive materials.  While these probes don't stop the eddy currents, they allow for their controlled manipulation and analysis.