This is exactly the situation I have experimented with in small motor
designs. If a magnet is moved past a coil, a voltage is induced across that
coil. If that voltage waveform is matched by an equal and opposite imposed
voltage on the coil, the ideal situation sees perfect cancellation of the
induced coil voltage. No power is consumed in this situation as it is like
connecting a power supply to a load that is already at the same potential
as the power supply - no difference in potential, no current. During this
sitaution all field interaction between the magnet and coil ceases, the
coil effectively 'dissapears', from the point of view of the magnet.
Regards, Bill.
At 20:05 5/10/98 -0500, Meat Truck wrote:
>Consider the following situation; A large magnet rotates in the vicinity of
>a large coil, so that the magnetic lines of force intersect the coil at
>right angles at some point in the revolution. If the magnet is on the side
>of the coil a sine wave output can be obtained form the coil. When the coil
>is shorted or powers a load the rotating magnet experiences a mechanical
>resistive force due to lenz law. The current established in the coil
>produces a magnetic field that opposes the relative movement of the
>rotating magnet. Now suppose for some reason we wanted to cancel the
>induced currents in the coil by sending an ac signal 180 degrees out of
>phase with that of the induced. Since the voltages would cancel out zero
>current draw would issue from this hypothetical cancellation generator,and
>therefore zero power would be consumed. Does anyone disagree with this
>assessment.
>Sincerely H Norris mnorris@akron.infi.net
>
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