The other two describe how the fields `` circulate '' around their respective sources ; the magnetic field `` circulates '' around electric currents and time varying electric fields in Ampère 's law with Maxwell 's addition , while the electric field `` circulates '' around time varying magnetic fields in Faraday 's law .
The other two describe how fields ` circulate ' around their sources . Magnetic fields ` circulate ' around electric currents and time varying electric fields , Ampère 's law with Maxwell 's correction , while electric fields ` circulate ' around time varying magnetic fields , Faraday 's law .