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In electromagnetism, an eddy current (also called Foucault's current) is a loop of electric current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a magnetic field. Eddy currents flow in closed loops within conductors, in planes ...
In the traditional version of eddy current testing an alternating (AC) magnetic field is used to induce eddy currents inside the material to be investigated. If the material contains a crack or flaw which make the spatial distribution of the electrical conductivity nonuniform, the path of the eddy currents is perturbed and the impedance of the ...
These are called eddy currents. On the lefthand side nearest to the other wire (1) the eddy current is in the opposite direction to the main current (big pink arrow) in the wire, so it subtracts from the main current, reducing it. On the righthand side (2) the eddy current is in the same direction as the main current so it adds to it ...
However eddy currents induced in the metal magnetic cores of transformers and AC motors and generators are undesirable since they dissipate energy (called core losses) as heat in the resistance of the metal. Cores for these devices use a number of methods to reduce eddy currents: Cores of low frequency alternating current electromagnets and ...
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. [2] The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object.
The direction of the circulation of eddy-currents is always such as to tend to oppose the relative motion. The eddy-current in the part receding from the poles tends to attract the poles forward or to drag this part of the disk backwards. The eddy-current in the part advancing toward the poles tends to repel those poles and to be repelled by them.
The term "electromagnetic testing" is often intended to mean simply eddy-current testing (ECT). However, with an expanding number of electromagnetic and magnetic test methods, "electromagnetic testing" is more often used to mean the whole class of electromagnetic test methods, of which eddy-current testing is just one. also useful for the ...
When a magnetic field moves through a conductor the movement induces an eddy current in the conductor. The flow of electrons in the conductor immediately creates an opposing magnetic field which results in damping of the magnet and produces heat inside the conductor similar to heat buildup inside of a power cord during use.