A long, hollow, cylindrical conductor (having inner radius 8.00 mm and outer radius 16.0 mm) carries a current of 14A distributed evenly across its cross section. A long thin wire which is coaxial with the cylinder carries a current of around 14A in the opposite direction. Determine the magnitude of the magnetic field:
i) 4.0 mm from the central axis?
ii) 12.0 mm from the central axis?
iii) 20.0 mm from the central axis?