Electromagnetism was a form of energy.
Michael Faraday was the director of the Royal Institution in the 19th century and studied electromagnetism. Lady Cowen enjoyed his lectures on the subject. (AUDIO: The Four Doctors)
Theodore Maxtible and Edward Waterfield based their experiments on James Clerk Maxwell's studies of electromagnetism. (TV: The Evil of the Daleks)
The Sidhe were electromagnetically-based lifeforms, which made them vulnerable to iron. (PROSE: Autumn Mist)
The warships of the Ice Warriors used a propulsion system based on electromagnetism that emitted no heat and was capable of playing havoc with primitive guidance systems. (PROSE: The Dying Days)
The ghosts on the Drum were sustained by an electromagnetic field. (TV: Under the Lake/Before the Flood)
Galvani was able to make frogs' legs move by subjecting them to electromagnetic spark. This inspired Percy Shelley to subject the body of the Eighth Doctor to an electromagnetic shock from the lightning, turning the Doctor into a monster. (AUDIO: Mary's Story)