1) The field strength varies from zero at the centre of the component to a maximum at the surface.
2) The field strength at the surface of the conductor decreases as the radius of the conductor increases when the current strength is held constant.( However, a larger conductor is capable of carrying more current.)
3) The field strength outside the conductor is directly proportional to the current strength. Inside the conductor, the field strength is dependent on the current strength, magnetic permeability of the material, and if magnetic, the location on the B-H curve.
4) The field strength outside the conductor decreases with distance from the conductor.
In the images below, the magnetic field strength is graphed versus distance from the centre of the conductor. It can be seen that in a nonmagnetic carrying DC, the internal field strength rises from zero at the centre to a maximum value at the surface of the conductor. The external field strength decreases with distance from the surface of the conductor. When the conductor is a magnetic material, the field strength within the conductor is much greater than it was in the nonmagnetic conductor. This is due to permeability of the magnetic material. The external field is exactly the same for the two materials provided the current level and conductor radius are the same.