Friday, July 4, 2014

Leiden Jar Physics Video: Lightning in a Bottle

The capacitor's history begins with the Leiden jar. Benjamin Franklin observed that electricity acts like a fluid, and so, in order to capture the electric fluid, an experiment was conducted at the University of Leiden

In the original experiment, a glass jar, held in the hand, had its inner lining coated with metal and this was charged electrically. Upon touching the inside with the other hand, the experimenter was surprised to receive a horrible shock! The electricity was saved in the jar like a liquid. This is the original "lightning in a bottle" experiment. You've heard of this phrase, right?

These days, the experimenter's hand has been replaced with an outside metal coating on the Leiden jar. The discharging hand has been replaced with a discharging wand. 

Image of a modern Leiden jar being discharged safely 

Most Leiden jars found in the high school classroom are of the plastic, dissectable variety, but many teachers do not know how to use them to their full potential or even safely.

                     A disassembled Leiden jar can be reassembled without loss of charge

In this video, I demonstrate how to safely dissect the Leiden jar and reassemble it, while maintaining the charge. This is one of the most surprising demonstrations in electrostatics.   

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