Consider an aluminum wire with 1 mm diameter below its critical temperature of 1.2 Kelvin. It's critical magnetic field is 0.01 Tesla. What is the maximum current in Amps that you can send down this wire for it to remain superconducting?
r=d/2 =0.5 mm =0.0005 m
I(max) = B(cr) c r /2 = 0.01•3•10⁸•0.0005 /2 = 750 A