pyörimisvirtoja

Pyörimisvirrat, known in English as eddy currents, are electrical currents induced within a conductor by a changing magnetic field. This phenomenon was first described by physicist Léon Foucault in 1851. Eddy currents are typically formed in conductive materials like metals.

The principle behind their formation is Faraday's law of induction. When a magnetic field that varies in time passes through a conductive material, it causes a change in magnetic flux within that material. This changing flux, according to Faraday's law, induces an electromotive force (EMF). Because the conductor is a closed circuit, this EMF drives electrical currents within the material itself. These circulating currents are known as eddy currents.

Eddy currents have several practical implications and applications. In some cases, they are undesirable. For instance, in transformers and electric motors, eddy currents can cause energy loss in the form of heat due to the electrical resistance of the conductor, leading to reduced efficiency. To minimize these losses, materials used in such applications are often laminated, meaning they are made of thin, insulated sheets. This increases the resistance in the path of the eddy currents, thereby reducing their magnitude.

However, eddy currents are also harnessed for beneficial purposes. They are used in induction heating, where the heat generated by eddy currents is used to melt or heat metals. Eddy current brakes, found in some vehicles and machinery, utilize the magnetic drag created by eddy currents to slow down moving parts. They are also employed in non-destructive testing (NDT) techniques to detect surface and near-surface flaws in conductive materials.