Created
electro-magnet at the
Royal Institution in London. With this he discovered
electromagnetic induction and the relationship between light and magnetism, called the
magneto-optic Faraday effect. Also developed the concept of the
magnetic field, and represented it with
lines of force.
Introduced words we still use today to discuss electricity: ion, electrode, anode, and cathode.
The unit farad is named after him, it is a measure of capacitance, an amount of electrical charge.