Attenuation of a Sinusoidal Magnetic Field in a Halfspace Conductor
Attenuation of a Sinusoidal Magnetic Field in a Halfspace Conductor
When a block of conductor is subjected to a changing magnetic field, a current is induced inside the conductor. This Demonstration shows this phenomenon when a sinusoidal magnetic field is applied to a halfspace conductor. The magnetic field of moderate frequency (and therefore, regarded as a near field) is assumed to be parallel to the conductor surface. The skin depth is determined by the frequency as well as the conductor parameters of conductivity and relative permeance . Taking the direction of the magnetic field as the -axis, the current is directed along the -axis. The spatial distributions of and (to which the electric field is proportional: =σ) are shown graphically.
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You can choose copper, iron, or brine (sea water) as the conducting medium. The amplitude of the exciting magnetic field is fixed at 1 A/m, but the frequency and the observation time (or phase) are variable. You can see an animation of the spatial distribution by changing the observation time.