What phenomenon causes magnetic domains to align in a ferromagnetic material?

The phenomenon that causes magnetic domains to align in a ferromagnetic material is the influence of an external magnetic field. In ferromagnetic materials, like iron, cobalt, and nickel, there are regions known as magnetic domains. Each domain acts like a tiny magnet, with a north and south pole, and they can be randomly oriented in the absence of an external field.

When an external magnetic field is applied, it exerts a force on these domains, causing them to reorient themselves in the direction of the field. As more domains align with the external field, the overall magnetization of the material increases, leading to a stronger magnetic effect. Once the external field is removed, many of these domains can remain aligned, resulting in a material that retains its magnetism, which is a characteristic property of ferromagnetic materials.

In contrast, other options do not significantly contribute to the alignment of magnetic domains. Electrical induction typically relates to the generation of current through electromagnetic induction, thermal agitation refers to the random motion of particles at higher temperatures that disrupts alignment, and mechanical stress can cause deformation but does not effectively align magnetic domains in the same manner as an external magnetic field.