Question

Niobium metal becomes a superconductor (with zero electrical resistance) when cooled below 5.1 K. The permeabilty of free space is 1.25664 × 10−6 N/A 2 . If superconductivity is destroyed when the surface magnetic field exceeds 0.11 T, determine the maximum current a 2.5 mm diameter niobium wire can carry and remain superconducting.

Answer 1

Answer:

687.5 A

Explanation:

We are given that

$\mu_0=1.25664\times 10^{-6}N/A^2$

Magnetic field,B=0.11 T

Diameter,d=2.5mm

Radius,r=$\frac{d}{2}=\frac{2.5}{2}mm=1.25\times 10^{-3} m$

$1mm=10^{-3} m$

We know that current in coil

$I=\frac{2\pi rB}{\mu_0}$

Substitute the values

$I=\frac{2\pi\times 1.25\times 10^{-3}\times 0.11}{1.25664\times 10^{-6}}$

$I=687.5 A$