Michael Faraday's discovery of electromagnetic induction in 1831 was probably one of the most important discoveries of all time. His core experiment is shown on the left: Around an iron core ring are wound two metallic coils. When suddenly applying a voltage (or removing the voltage) to one of them (the coil to the front), it induces a spike of electromotive force and thus measurable voltage in the other coil. The core principle is that the applied voltage generates a current (red circular arrow) in the first coil, which generates a magnetic field in the iron ring (blue circular arrow), which then induces a voltage in the second coil. This effect is the basis of all our electric industry today, because it allows to generate electric voltage from mechanical work, as shown by the animation of a dynamo with self-generated magnetic field (light blue lines) in the middle. It is also the basis for all electromagnetic transformers (shown on the right), which can be found everywhere in our daily life.