Hello,
The real problem is :
I have magnetic material (magnetized) that is deforming in time (let's say, because of vibration) with respect to the reference frame of the lab, I want to know, what is the induced EMF in a coil (stationary in the lab reference frame) ?
The simplified problem (see picture) :
I have two cases :
In this case the induced EMF in the receiver is given by the general magnetic induction law ( A is the magnetic vector potential). Where fields are always expressed in the reference frame Ro.
2. The receiver is now stationary in Ro and the emitter is moving (deforming).
To keep things general the emitter is a deforming magnetic 3D body.
What is the induced EMF in the receiver coil ?
Thank you in advance.
Hello Sir,
It is always the same:
EMF = d(PHI)/dt, where
EMF : the induced voltage
PHI : The magnetic flux through the coil. (If the coil has N windings, it is N times the magnetic flux for one winding).
The formulae is independent of the source of the flux deforming or not, and also indepenent of the coil deforming or not.
To calculate it numerically, I guess you need to take the area-integral to determine the flux through the coil, and then compute the (first) derivate.
Cheers, Henri.
Thank you for you answers Henri Cloetens and Preston Guynn .
I know I may not have been clear and detailed in my question, but the problem is to express the variation of flux as a function of the velocity of the emitter, as done in the first case, where we can se the transformer and the motional EMFs.
Thank you in advance
Work out how the flux through the receiver loop varies with time. This gives you d(PHI)/dt. You can get the flux variation from the change in shape and/or position of the metal core or the emitter, as Henri has already said.
To be exact there should be a minus sign in the equation, but for that to mean anything you need to know which direction is positive! To do that use Faraday's law and Lenz's law, but you probably don't need to know the direction of the current as it is ac from vibration.
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