Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What causes magnetism in materials?

1. The speed of electron flow through the material

2. The arrangement of electrons' spins

3. The resistance offered by the material

4. The presence of magnetic fields

The correct answer is: The arrangement of electrons' spins

The cause of magnetism in materials is fundamentally linked to the arrangement of electrons' spins within atoms. Electrons possess a property known as "spin," which contributes to their magnetic moment. In most materials, the spins of electrons are randomly oriented, which cancels out any magnetic effects. However, in ferromagnetic materials such as iron, cobalt, and nickel, certain conditions allow for the alignment of these spins over larger regions of the material. When a significant number of adjacent electron spins are aligned in the same direction, it generates a net magnetic field, thus making the material exhibit magnetism. It's important to note that while the speed of electron flow can be related to electric current and contribute to electromagnetism, it is not the primary cause of magnetism in static materials. Resistance does affect how easily a current can flow through a material, but again, it does not directly cause magnetism. The presence of external magnetic fields can influence the behavior of materials, but the intrinsic magnetism comes from how the electrons are arranged and their spins within the substance itself.