Question

The element niobium, which is a metal, is a superconductor at temperatures below

9 K . This means that at such low temperatures a niobium wire has no electrical resistance. The superconductivity of the wire, however, is destroyed if the magnetic field at the surface of the wire exceeds 0.10 T . What is the maximum current in a straight superconducting niobium wire of radius 1.5 mm ? You may assume that all the current flows in the center of the wire.

A) I= 1250 A                  r= 2.5mm

B) I= 500 A                  r= .50mm

C) I= 300 A                  r= 1.0mm

Part E

Identify whether the above niobium wires would be superconducting at temperatures below 9 K. Each diagram shows the value of the current in the wire and the wire's radius.

Answer 1