“Electromagnetism” is a silent educational film from the late 1920s that explains the basic principles of electromagnetism using simple animations, diagrams, and live-action demonstrations.

Electromagnets have some advantages over permanent magnets. For example: they can be turned on and off the strength of the magnetic field can be varied These properties make electromagnets useful ...

Electromagnetism is due to the magnetic fields ... can be used to make motors spin and loudspeakers produce sound, for example.

Another example involves wave equations ... for defects in a crystalline lattice and a well-known formula from electromagnetism. They demonstrated that the fields representing the strain generated ...