A long cylindrical conductor of radius R carries a current I as shown in Figure P30.29. The

Question:

A long cylindrical conductor of radius R carries a current I as shown in Figure P30.29. 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 = br, where b is a constant. Find an expression for the magnetic field B
(a) At a distance r1 (b) At a distance r 2 > R, measured from the axis.