Farraday's Law states V= -N.flux/time , if this calculates voltage how does one determine amplitude?
Amplitude of what?
amplitude of the induced electric charge
I assume you are talking about a loop of wire. It presumably has a certain resistance. The voltage produces a current in the wire. The current is related to the amount of charge that flows by...? (what's the definition of current?)
The thing is, that the function that describes the magnetic field of the object is not necessarily a wave.
The vector field function, from which you obtain the voltage of the object, varies according to the speed of the particles moving inside of it, depending on the nature of this movement, the function will take an specific "form" and this is not necessarily a periodic one, and as such, there is no thing as an "amplitude" on all cases, thought of curse, if the source of this particles is an AC current, in which case, the energy, and in consequence, the speed of the particles would change with time forming a periodic function, the object (inductor) would experiment too, a periodic variation on both it's voltage and magnetic flux; in this case, you can "cut-out" an oscillation of the wave function, get the derivative (with respect of time of course) of the voltage and see on which point inside the interval of the oscillation this derivative is equal to 0, the value for "V" on that "t" value would be the amplitude (you can do something similar too for the other functions of the system, like magnetic flux, except, I believe, for the current, because the inductor seems to oppose the change of current).
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