MIT Physics Demo -- Jacob's Ladder and the Melting Nail
A solenoid is connected to AC power. First, a 10,000-turn coil is placed over the solenoid, but is not connected to the power source. However, the solenoid still induces current in coil, creating very high voltages because of the high number of turns. The rabbit ear spark gap creates an arc that moves from the bottom of the gap to the top (an effect known as Jacob's Ladder). This is due to convection and will not work upside-down
Next, a 1-turn copper loop (containing a gap filled by a nail) is placed over the solenoid. This time the induced current is very large, rather than the voltage. This high current encounters strong resistance in the nail creating temperatures so hot that the nail is melted.
