Question

Problem 24.11 Part A The element niobium, which is a metal, is a superconductor (i.e., no electrical resistance) at temperatures below 9 K. However, the superconductivity is destroyed if the magnetic field at the surface of the metal reaches or exceeds 0.10 T What is the maximum current in a straight, 2.8-mm-diameter superconducting niobium wire? Submit My Answers Give Up Provide Feedback Continue

Answer 1

The magnetic field of a long straight wire is B = µ0I /2πr ,

where r is the distance away from the center.

So, at the surface of the wire, when r = d, the current in the wire is

I = 2πBd/µ0

I = 2πBd/µ0 = 2π × 0.10 × 0.0014/ 4π × 10−7 = 700 A