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Using the Meissner effect, where a superconductor, having no electrical resistance, is suspended when applied, under the correct conditions, the repulsive force of the magnet.

Newton's third law states a force will have an equal, but opposite reaction, yet I don't see any forces directly acting on a magnet when levitating the superconductor.

Is there an opposing, opposite force during this interaction?


Comment Response (1):

"The magnet is presumably pushed down with the same force that it is pushing the superconductor up = the weight of the superconductor?", (Martin Beckett)

By Newton's 3rd Law this should be, but is it that emitting magnetic currents generates a downward force, or that the repulsive forces somehow create an equal force on the magnet, etc.? I'm unaware of any forces or processes within this process that would produce an opposing force. So generally this is the idea was was hoping you could elaborate on.


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  • $\begingroup$ The magnet is presumably pushed down with the same force that it is pushing the superconductor up = the weight of the superconductor? $\endgroup$ – Martin Beckett Nov 2 '17 at 5:03
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There is an equal and opposite force. The Meissner effect acts on both the magnet and the superconductor. You can see this in the fact that a magnet suspended over a superconductor will levitate just as a superconductor will levitate over a magnet. Or a superconductor and a magnet placed next to one another on a table will accelerate apart from each other.

The surface currents generated by the Meissner effect produce a magnetic field that repels the magnet. Similarly these currents feel a repulsive force from the external applied magnetic field.

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