1. The problem statement, all variables and given/known data Use Ampere's Law to show that the equation for the magnetic field inside a current carrying wire is (1/2)μJr where J is the current density (assumed constant). 2. Relevant equations ∫B*ds=μI 3. The attempt at a solution ∫B*ds=μI B*ds=B(ds)cosθ I think θ is 0 in this situation? ∫Bds=μI I believe r is length. If so would I=Jr? ∫Bds=μJr From here I don't know what to do. What would my limits of integration be?