Electromagnetism

Electromagnetism was a form of energy. It was carried by electromagnetic radiation (TV: The Mutants) in the form of waves (TV: The Space Pirates), and could create an electromagnetic field. (TV: The Claws of Axos)

According to Zoe Heriot, electromagnetic waves travelled at right angles to the direction of propagation at a speed of 186,282 miles per second. (TV: The Space Pirates) Electromagnetic disturbances could be detected using an oscilloscope. (TV: The Pirate Planet)

Devices that made use of electromagnetism included cyclotrons (TV: The Claws of Axos) and Continuous Event Transmuters. (TV: Nightmare of Eden)

History
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 in June 1816, turning the Doctor into a monster. (AUDIO: Mary's Story)

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 in 1866 on James Clark 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)

In 2119, the ghosts on the Drum were sustained by an electromagnetic field. (TV: Under the Lake/Before the Flood)