Electrostatics experiments

Light objets attraction Hanging balloon Trickle of water Electroscope and versorium Charging and discharging by contact Charging by induction Points power Two sorts of electric charges (a) Two sorts of electric charges (b) Conduction Sign of Charges Electrostatic chime Electrophorus Faraday  Cage
French page

by Michel Maussion - University of Nantes - France

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Sign of the charges

Several methods are possible to find the sign of the charge of an object  :

By comparaison using the electroscope

In the former experiments it has been observed that the electroscope takes a charge like the one of the object if it is charged by contact or by points and an opposite one by induction. It has also been seen that a new object coming further near, has the same sign that the electroscope if the leaves begin to shut, and the opposite sign if they part more. So, knowing with certainty the charge of one object is enough to deduce that of all the others.

Directly with a multimeter

Get back the support and the paper of the previous experiment and get a cheap multimeter.


Insert one end of the paper strip into the straw of the support and the other end into the born +. Leave the thread of the born - (COM) running on the table.

Select the calibre 200 mV =.

Bring quickly the charged object to test nearby the top of the support : the displayed sign is that of the charge.

Take it off : the new sign is opposite.


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