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Old November 16th 04, 02:49 PM
Richard Harrison
 
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Curious John wrote:
"Can someone please provide a correct near field equation that I can
understand?"

The relation between the current in a wire and the magnetic field
intensity (H) around it at any distance (r) is:

H = 2I / r
I is the current in a long straight wire.

The magnetomotive force around a complete contour around a wire is: 4Pi
(I)

If the current is changing, the magnetic field is likewise changing. An
electric field is induced in the space around the wire. The voltage
induced in a wire properly immersed in the field is:

-d Phi /dt

The induced voltage is proportional to the rate of change of the
magnetic flux and is negative, that is it opposes the changing flux.

When an electric field is imposed on a dielectric, it places an
electrical strain in the dielectric. This causes a dielectric
displacement current (D):

D = dielectric constant x volts/m of the electric field. So D is
equivalent to an electric flux density. Displacement current is greater
in materials with larger values of dielectric constant. The value for
air or space is one.

Best regards, Richard Harrison, KB5WZI