Electromagnetism

Passing electricity through a coil of wire wrapped around an iron core will produce an electromagnet. Similarly, moving a magnet inside a coil of wire will cause an electric current to flow; a process called electromagnetic induction.

Combining these two ideas, Michael Faraday invented the transformer in 1831, in London. Transformers can change the output voltage to be either higher or lower than the input voltage by adjusting the turns ratio between the primary and secondary coil.

The electric motor, also invented by Michael Faraday, works because a current carrying wire can experience a force when placed in a magnetic field. The direction of the force can be found using Fleming's left-hand rule.