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Franklin's Bell


Electrostatic discharge Classes Used: PHYS 100, PHYS 153, Phys 102


To illustrate electrostatic discharge


Stand with pendulum (as seen in picture) Van de Graaff machine


Set stand facing the Van de Graaff so that the ball is hanging equidistant from both metal surfaces. Start generator. The ball will charge and discharge, thereby being attracted and repelled to the Van de Graaff in a bell like motion. Named after a system that Benjamin Franklin reportedly used to tell when lightening was coming.

Use a helium-filled mylar balloon for a human version of this demo. Place the balloon (tied to a weight on on the ground) between the Van de Graaff and the volunteer. The person will act as the discharge as the balloon sways back and forth. Warning: you will be shocked!


please give sufficient notice to get helium balloon, or provide your own.

Demo room information

Location In front of OPQ
Maker Unknown
Current State Working
demonstrations/5_electricity_and_magnetism/5a_electrostatics/franklins_bell/start.txt · Last modified: 2020/03/02 22:13 by demoroom