I heard it was possible to detect a flaws in conductive materials using two coils carrying the same current in opposite directions.
More precisely, I read it was possible to do so by moving a conductive material at a constant speed on the axis of the two coils, and by measuring the voltage on a third smaller coil (also placed on the same axis).
I understand that the first two coils create a magnetic field, and that moving the material will therefore cause eddy currents. I also get that the presence of flaws will change those currents.
But concretely, how will we be able to know whether the conductive material does or does not have flaws ?
Thank you for your help.