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Khan Academy
Khan Academy: Pith Ball Electroscope
This is a demonstration of a primitive device for measuring electrostatic force. [0:38]
Khan Academy
Khan Academy: Electrostatics: Discovery of Triboelectric Effect
Our ancestors noticed that when amber was rubbed against fur it attracted small objects. Why is this? [0:52]
Khan Academy
Khan Academy: Electrostatics: Pith Ball Electroscope
A primitive device for measuring electrostatic force. [0:39]