Briefly describe the phenomenon of magnetic hysteresis, and why it occurs for ferromagnetic and ferrimagnetic materials.

Answer: Magnetic hysteresis is a phenomenon that occurs in ferromagnetic and ferrimagnetic materials, where the magnetization of the material does not follow the applied magnetic field but exhibits a loop-like behavior known as hysteresis loop. It occurs due to the nature of magnetic domains and their interactions with each other and the applied field. When a magnetic field is applied, some domain boundaries move, causing the domains to grow or shrink. However, when the field is removed, these boundaries do not immediately return to their original positions, leading to a lag between the magnetization and the applied field. This behavior is due to the energy barriers that must be overcome for the domains to change their magnetization orientation.