A long, cylindrical conductor of radius?R?carries a current?I?as shown in the figure below. The current density?J, however, is not uniform over the cross-section of the conductor but is a function of the radius according to?J?=?5br4, where?b?is a constant.Find an expression for the magnetic field magnitude?B?at the following distances, measured from the axis. (Use the following variables as necessary:?
?0,?r1,?r2,?b,?R
.)
(a)?r1?<?R
B=
(b)?r2?>?R
B=