Create high-voltage sparks of varying lengths with this classic demonstration apparatus.

• 25 mm vs. 50 mm refers to the length of the spark which can be produced across the gap between the electrodes

Consisting of a primary coil with few turns and a secondary coil with many turn, induction coils convert low voltage direct current to high voltage sparks through the use of an interrupter. The rapidly fluctuating magnetic field from the primary coil induces a pulsing voltage high enough to cause a spark in air. Vividly demonstrate the principles of induction and transformers with this classic apparatus.