Electromagnetism

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)