Pyörrevirrat

Pyörrevirrat, also known as eddy currents, are electrical currents induced within bulk materials by a changing magnetic field. This phenomenon is a direct consequence of Faraday's law of induction. When a conductor, such as a piece of metal, is exposed to a varying magnetic flux, a voltage is generated across the conductor. This voltage can drive current flow within the conductor itself, creating circulating currents known as pyörrevirrat.

The magnitude of these induced currents depends on the rate of change of the magnetic field, the resistivity of the material, and the geometry of the conductor. Materials with lower resistivity will experience stronger pyörrevirrat for the same changing magnetic field. The induced currents are always in a direction that opposes the change in magnetic flux that produced them, as described by Lenz's law.

A significant consequence of pyörrevirrat is the generation of heat due to the electrical resistance of the material. This heating effect, known as Joule heating, can be both a useful property and a detrimental side effect. In applications like induction cooktops and magnetic braking systems, the controlled generation of pyörrevirrat is utilized for heating and energy dissipation. Conversely, in transformers and rotating electrical machinery, pyörrevirrat can lead to undesirable energy losses and overheating, necessitating measures to minimize their formation, such as using laminated cores made of thin, insulated sheets of conductive material.