A hollow cylindrical (inner radius = 1.0 mm, outer radius = 3.0 mm) conductor carries a current of 80 A parallel to its axis. This current is uniformly distributed over a cross section of the conductor. Determine the magnitude of the magnetic field at a point that is 2.0 mm from the axis of the conductor.

The magnetic field is  

Explanation:

From the question we are told that

     The inner radius is  

      The outer radius is  

       The distance from the axis of the conductor is

      The current carried by the conductor is  

According to Ampere's circuital law , the magnetic field at a point that is    from the axis of the conductor

Where is the permeability of free space with a value of

substituting values

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.