1. The problem statement, all variables and given/known data A long, straight conducting wire of radius R has a nonuniform current density J=J0*r/R, where J0 is a constant. The wire carries total current I. Find an expression for J_0 in terms of I and R. Find an expression for the magnetic field strength inside the wire at radius r. 2. Relevant equations J=I/A B*ds = u0*I 3. The attempt at a solution So from my book it looks like J0=I/A which is Jo=I/(pi*R^2) which says it is off by a multiplication factor not sure where Im going wrong here. As for the second portion I got B= uo*I*r/(2*pi*R^2) which is also wrong so any help on this would be much helpful.