Which phenomenon serves as our primary source of electric power?

The primary source of electric power is magnetism, particularly through the principles of electromagnetic induction. This phenomenon, discovered in the 19th century, showcases that when a conductor, such as a copper wire, moves through a magnetic field, it induces an electric current within the conductor.

This principle is foundational to the workings of generators and transformers, which are pivotal in generating and distributing electrical power. Power plants commonly utilize this concept by rotating turbines within magnetic fields to produce electricity efficiently.

While friction can produce static electricity, it is not a reliable or sustained source of electric power. Gravity is essential in hydroelectric power generation, but it's not the direct source of electric power. Heat can produce electricity as seen in thermoelectric generators or power plants, but again, this is not the primary method of generating electric power in most applications. Thus, magnetism stands out as the core phenomenon behind electric power generation.