Before revision: upright=1.7|Magnetic field (green) created by a primary winding (red) in a typical magnetic core transformer or inductor, with the iron core C forming a closed loop, possibly with air gaps G in it.
After revision: upright=1.7|Magnetic field (green) created by a current carrying winding (red) in a typical magnetic core transformer or inductor, with the iron core C forming a closed loop, possibly with air gaps G in it.