The Jacob's ladder is a spectacular demonstration. It is colourful and slightly dangerous. It is sourced by a 10 000 Volt power supply which is fed to one of the metal strips, encased for your protection. The electrical pressure is not fed to the strip in a steady stream like a battery, but in regular pulses. Electricity always goes from where there is a lot to where there is less. For example, the accumulation of electric charge in the sky (lightning) tries to find its way to ground, preferably through the path of least resistance. Air is usually a poor conductor so the electricity finds better paths, like a tree in a field or a tall skyscraper. In our Jacob's Ladder, the second metal strip is connected to ground, and since it is the closest object around the electricity will jump from one strip to another forming a beautiful arc. As the electricity jumps across it heats the surrounding air. As warmer air is a better conductor of electricity than the cooler air the electricity will arc through the rising heated air.
(Remember to ground the Jacob's ladder before handling it)
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