The electromagnetic soda can crusher may not be entirely practical, but it sure is an impressive display of electromagnetism and capacitors. The can crushing effect results from the repulsion of two magnetic fields. Initially, a very large 50 microFarad 25 kilovolt capacitor is charged to 10 kilovolts. There is a direct relationship between the voltage level and the crushing force. Once the desired voltage is reached, a spark gap connects a small coil to the very large capacitor. As a frame of reference for the size of the capacitor, consider that the capacitor took up one quarter of the space in the marble column in which it is enclosed. The coil is a thick wire which circles the center of the soda can. The can crusher built by Resonance Research Corporation has timing controls for push button charging and firing. When the spark gap switch fires, the capacitor discharges a tremendous amount of current through the coil (roughly 100,000 amperes.) This current discharge creates a magnetic field around the coil. Flux lines pass through the cross section of the can causing current to be induced and to flow around the can. The induced current creates its own magnetic field which opposes the magnetic field from the coil. Between the two magnetic fields, the can is now subject to one magnetic field pushing inward on the can and one magnetic field pushing outward on the coil. When the force becomes strong enough, the can is crushed. Steam emitted from the soda can as it was crushed.