If we write the Biot Savart law as
B(r)=μ0/4π∫(J(r')xn/n2)dV'
where B is the magnetic field which depends on r=(x,y,z), a fixed point, J is the volume current density depending on r'=(x',y',z'), and n=r-r', a vector from the volume element dV' at r' to the point r. Note we integrate over the...