What does magnetism refer to?

Magnetism refers to the invisible force that can accomplish mechanical work through the processes of attraction and repulsion. This phenomenon arises from the motion of electric charges, which generates magnetic fields. For example, magnets can attract certain metals, such as iron, due to the alignment of atomic structures within those materials. When two magnets come together, they either attract each other or repel each other based on their polarities, demonstrating this fundamental force in action. This ability to exert force at a distance and perform work without direct contact is a key characteristic of magnetism and plays a crucial role in various applications, from electric motors to data storage devices.

The other concepts, while related to physics and technology, do not accurately define magnetism. The flow of current through a circuit relates more to electricity than magnetism, battery charging is a process involving chemical energy and electricity, and the direct conversion of heat into electricity concerns thermoelectric phenomena rather than magnetic forces. Thus, the definition of magnetism as an invisible force that manifests through attraction and repulsion captures the essence of its meaning in physics.