Demos: 5A-32 Separable Leyden Jar

The apparatus consists of two metal cups separated by a glass cup. Charge the Leyden jar using the electrostatic generator. Once it is charged, remove the ESG and lift the inner cup using a glass hook. The glass cup may be removed by hand. After the metal cups are separated, they are brought into contact with each other and no spark occurs. But when the apparatus is reassembled, a vigorous spark can be obtained when the two metal cups are shorted. This illustrates that the energy is stored as static charge in the insulator.

Directions: Leyden jars can store considerable energy, exercise some caution in doing this demo. Avoid making direct contact with the two cans simultaneously. Use glass hook for safety.

Suggestions for Presentation: This can have all the appearance of a “magic show.” Once the jars are charged, make a big show of avoiding contact with the metal cans. Bring them together very slowly and carefully, as if expecting a big spark. When nothing happens, express dismay that all the charge leaked off. Then suggest reassembling the apparatus to start over. “Just to be safe,” short out the two cans with a shorting lead. The large spark that occurs will be unexpected and dramatic. You may repeat the demo a few times for effect.

Applications: Leyden jars are used for storing charge.

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