Electronics Engineering (ELEX) Board Practice Exam

The behavior of ferromagnetic domains under an applied magnetic field results in what phenomenon?

1. Magnetization

2. Hysteresis

3. Electromagnetism

4. Repulsion

The correct answer is: Hysteresis

The phenomenon associated with the behavior of ferromagnetic domains under an applied magnetic field is best described by hysteresis. When a ferromagnetic material is exposed to a magnetic field, its magnetic domains—regions where the magnetic moments of atoms are aligned—realign in the direction of the field. This realignment is not instantaneous and depends on the strength and direction of the applied magnetic field as well as the history of exposure to the field. Once the external magnetic field is removed, the domains do not return entirely to their original random orientations, which results in the material retaining some magnetization even in the absence of the applied field. This property is characterized by a hysteresis loop when the magnetization of the material is plotted against the external magnetic field strength. The area within this loop represents energy losses in the material due to factors such as friction and resistance, indicating how the material behaves across cycles of magnetization and demagnetization. This behavior is distinct from other concepts such as magnetization, which directly refers to the extent of magnetization of the material itself; electromagnetism, which deals with the interaction between electric currents and magnetic fields; and repulsion, which describes the force experienced between similar magnetic poles but does not encapsulate the broader and