I haven't seen anyone derive the magnetic field density (B) using ampere's law, only using Biot-Savart Law
any reason why?
if we cut the loop and loop at one end (of the new cut) and treat it as if it was a current carrying wire, then by ampere's law we'd get:
B = u*I / 2*pi*r
but however by the Biot-Savart Law we actually get
B = u*I / 2*r
anyone know why?