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Eddy who?

Some answers

A more detailed explanation is given using the diagram below.

The aluminium sheet with open slots is in a uniform magnetic field that is coming out of the page. It is moving to the left and has a small force to the right acting on it.

The open slots in the aluminium plate prevent a circular eddy current from forming, so the plate’s motion is unaffected and it keeps swinging.

Without slots in the metal, circular eddy currents are easily formed, as shown in the diagram below.

A wooden rod with a solid copper sheet is swinging in a magnetic field that is coming out of the page. In the first position it is swinging to the left and is half out of the magnetic field. An anti-clockwise circular eddy current has been produced in the copper sheet to resist this motion. In the second position it is swinging to the right and is half out of the magnetic field. A clockwise circular eddy current has been produced in the copper sheet to resist this motion. In the first position it is swinging to the right and is half out of the magnetic field. A clockwise circular eddy current has been produced in the copper sheet.

The solid copper sheet moving in the magnetic field and the associated eddy currents produced by this motion.

In the first position AB

The metal sheet is swinging to the right and has just entered the magnetic field. A clockwise, circular eddy current is induced in the copper sheet to resist this motion.

In the second position CD

The metal sheet is still swinging to the right and is half way out of the magnetic field. An anti-clockwise, circular eddy current is induced in the copper sheet to resist this motion.

If you use the right hand solenoid rule or the right hand motor rule you should arrive at the same direction of the induced current.

To look at some eddy currents in action, follow the link below:

www.ndt-ed.org/EducationResources/HighSchool/Electricity/eddycurrents.htm

A short summary of eddy currents

Properties of eddy currents.