Ruhmkorff spark inductor, named after its inventor Heinrich Daniel Rühmkorff, a German-French electrical engineer. It is used for the inductive generation of high voltage and provides elctrical discharges with greater energy than the electrophorus. It consists of a transformer powered by batteries. An interrupter, the so-called Wagner hammer, opens and closes the electric circuit electromagnetically. The strong changes in the magnetic field generate high voltage pulses over 100 kV. Rühmkorff exhibited his spark inductor for the first time at the international industrial exhibition in Paris in 1855. In addition to the scientific application, spark inductors were also exhibited as children's toys or for amusement at fairs.