Question

Using scientific language, explain in your own words how magnetism works. Then, provide two real-life examples of how you use magnets and describe their purpose. Write your response in complete sentences.

Answer 1

Magnetism is a physical phenomenon that arises from electric charges in motion and from intrinsic quantum properties of elementary particles. At the microscopic level, electrons have an intrinsic magnetic moment associated with their spin and a smaller contribution from their orbital motion around nuclei; these microscopic moments produce a magnetic field. In many materials, quantum-mechanical exchange interactions cause groups of atomic magnetic moments to align parallel within regions called domains, and when a majority of domains are aligned the material exhibits a net, or macroscopic, magnetization (this is the basis of ferromagnetism). Moving electric charges, such as current in a wire, also generate magnetic fields described classically by the Biot–Savart law and Maxwell’s equations; those fields exert forces on other moving charges and on magnetic dipoles according to the Lorentz force law and the torque on a magnetic moment. Magnetic field lines are a convenient way to represent the direction and relative strength of the field; they emerge from a magnetic north pole and enter a magnetic south pole, and isolated monopoles have not been observed. Different materials respond differently to applied magnetic fields: ferromagnetic materials can become strongly magnetized, paramagnetic materials are weakly attracted, and diamagnetic materials are weakly repelled.

I use a small permanent magnet on my refrigerator to hold up reminders and grocery lists, where the magnet’s purpose is to provide a steady attractive force between the paper and the metal surface so the paper stays in place. I also rely on magnets inside the speakers of my phone and headphones, where the interaction between a permanent magnet and a current-carrying coil converts electrical signals into mechanical motion of the diaphragm, producing sound.