PURPOSE: To demonstrate the existence of electric fields and to map them semi-quantitatively.
DESCRIPTION: A small conducting sphere on an insulating pole is connected electrically to an electroscope. The strength of the electric potential can be mapped out by observing the deflection of the electroscope as the metal ball sensor is moved about in the region of the Van de Graaff dome. After drawing a spark the electroscope must be grounded to reset it to neutral potential.
REFERENCES: (PIRA unknown.)
EQUIPMENT: Van de Graaff generator, small conducting ball on plastic pole, electroscope and point projection source.
SETUP TIME: 5 min.
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