If I were to attempt to calculate the magnetic field produced by an infinite wire at a certain point, I would use Biot-Savart Law to approximate the magnitude of the field at point($P$) away form the wire. However, would the same equation become valid for a superconductor of both types I & II?

How would the Meissner effect alter the equation? If I consider the case of a large diameter copper wire of radius(r) Biot-Savart equtions:

$$B_p = \frac{\mu_0i}{2\pi R} $$

Where $R = L + r$, L being the distance of point $P$ away from the wire added by the wire's radius. In the case of a superconducting wire, Meissner's effect that's expelling the field from within the superconducting wire, would $r$ be irrelevant if the superconductor had a large diameter(or radius)?

Would that result to a stronger field at the same $L$ and the same current applied to both the superconductor & RT-conductor(copper)?


1 Answer 1


As long as you are outside the wire, Biot and Savart law takes the same form regardless of the physical details of the wire. Think about it, even for metallic wires, different materials and casting method may result in different distribution of current inside the wire, but outside the wire, you still use the same law, dependent only on the total current passing through the wire.


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