Electromagnet is a closed magnetic circuit, composed of the coil, yoke, iron core (pole), and pole head.
Energized electrically conductive winding (coil) can generate a magnetic field, the internally arranged irregular ferromagnetic metal atoms of the iron core (pole) rearrange regularly with the action of the external coil’s magnetic field, together point in one direction, thereby these ferromagnetic metal atoms are magnetized to increase the magnetic flux so that a considerable amount of the magnetic flux Φ is produced during the iron core, the yoke, and the air gap. When the control power supply current is changed, the controllable high magnetic field is formed between the air gap of two poles.
Apply to Hall effect studies, magnetoresistance effect studies, magnetostriction studies, torque magnetometer, force method magnetometers, VSM, etc.
Refer to https://www.dexinmag.com/electromagnet