Why is every piece of $\mathrm{Fe}$ not a magnet, even though $\mathrm{Fe}$ is a magnetic material?

• A. Because $\mathrm{Fe}$ cannot be influenced by external magnetic fields.
• B. Because $\mathrm{Fe}$ atoms do not have any magnetic moments.
• C. Because the magnetic domains in ordinary $\mathrm{Fe}$ are randomly oriented, so their magnetic effects cancel each other out.
• D. Because $\mathrm{Fe}$ only becomes magnetic at extremely high temperatures.

Answer: (C)

Verified step by step guidance

1. Understand that iron (Fe) is a ferromagnetic material, meaning its atoms have magnetic moments due to unpaired electron spins.
2. Recognize that in a piece of iron, these atomic magnetic moments group together in regions called magnetic domains, where the moments are aligned in the same direction.
3. Note that in an unmagnetized piece of iron, these magnetic domains are oriented randomly, so their individual magnetic fields cancel out overall, resulting in no net magnetism.
4. When an external magnetic field is applied, it can cause the domains to align more uniformly, making the iron piece behave like a magnet.
5. Therefore, not every piece of iron is a magnet because the random orientation of magnetic domains prevents a net magnetic effect unless influenced by an external field or other processes.