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.
B*ds = u0*I
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.