What are eddy currents?

Question

Please describe how they are induced...with a few examples...n' no links plz!!!

Answer 1

when a mass of metal moves in a magnetic field or when the magnetic field through a stationary mass of metal is altered, induced current is produced in the metal. this induced current flows in the metal in the form of closed loops resembling 'eddies' or whirlpool. hence this current is called eddy current.
this was first observed by Foucault in 1895.
When a conductor in the form of a disc or a metallic plate swings between the poles of a magnet, eddy curents are set up inside the plate. this current acts in a direction so as to opppose the motion of the conductor with a strong retarding force, that the conductor almost comes to rest.If the metallic plate with holes drilled in it is made to swing inside the magnetic field,the effect of eddy current is greatly reduced consequently the plate swings freely inside the field.Eddy current can be minimised by using thin laminated sheets instead of solid metal.
here is an example for how it is used:
ELECTROMAGNETIC BRAKES:
A metallic drum is coupled to the wheels of a train. the drum rotates along with the wheel when the train is in motion. when the brake is applied, a strong magnetic field is develod and hence, eddy currents are produced in the drum which oppose the motion of the drum. hence, the train comes to rest.
here is how eddy current is avoided:
IN TRANSFORMERS:
The varying magnetic flux produces eddy current in the core. this leads to the wastage of energy in the form of heat. this loss is minimised by using a laminated core made of stelloy, an alloy of steel.

I feel this info will be sufficient for u.If not tell me I can give u more details.If u feel its too lengthy give ur comments.

Answer 2

Eddy Currents are small circulating electrical currents are induced in a material by a coil which is energized by an alternating current, creating a alternating magnetic field around it. When this coil is placed near a conductive material, lets say a metal, inside the metal these eddy currents are induced. The eddy currents then create their own magnetic field that opposes the first magnetic field.
Eddy Currents are used to detect cracks in materials cos a crack distorts the eddy currents and therefore the strenth of their magnetic field, all this can me measured by machines, which allows users to accurately detect cracks in metal.

Answer 3

Eddy currents occur in flat pieces of metal. They are induced by magnetic flux, i.e., electrical motors in the area, transformers operating, any kind of coiled wire with a fluctuating current, will all produce changing magnetic fields which can then produce eddy currents in the piece of metal.

Answer 4

Eddy Currents

Click on the URL below for additional information of eddy currents.