Why is the magnetic field strength greater inside a current-carrying loop of wire than about a straight section of wire? Each time an electron goes around the loop, it adds its magnetic field to the magnetic field of the loop, and every single electron goes around the loop many times. The magnetic field of each segment of wire in the loop, due to electrons moving in the wire, adds together inside the loop, thereby making the field become bunched up. Negative electrons move in one direction around the loop, while positive protons move in the opposite direction, and their magnetic fields add inside the loop. Electrons going around a loop align their spins and their individual magnetic fields with the fields of adjacent electrons