Niobium metal becomes a superconductor when cooled below 9 K. Its superconductivity is destroyed when the surface magnetic field exceeds 0.100 T. In the absence of any external magnetic field, determine the maximum current a 5.68-mm-diameter niobium wire can carry and remain superconducting.

The current is  

Explanation:

From the question we are told that

   The  diameter of the wire is  

    The  magnetic field is  

Generally the radius of the wire is mathematically evaluated as

substituting values

Generally the magnetic field is mathematically represented as

=>    

Here is the permeability of free space  with value

substituting values

=>    

=>    

divide the right side by the left side

0.024÷1.2=0.02 for example

trig 15.3 cos