Existence of positive and negative charge
Demonstration of the existence of positive and negative electric charge. Charge separation by impact and friction.
Leybold manuals:
Apparatus for measuring electrostatic charge. The charge applied to the metal Faraday cup charges a capacitor (here 10 nF), and the voltage across this capacitor is measured using an operational amplifier. In this case, 1 V corresponds to 10 nC. The grounding rod is used to discharge the capacitor or to ground the experimenter.
Plastic rods made of acrylic glass and PVC.
Leather, PE foil and paper.
Grounding the Faraday cup discharges the apparatus.
At the start, the rods are nearly neutral.
At the start, the rods are nearly neutral.
When the rods are struck against each other, they become charged. One of them charges positively.
When the rods are struck against each other, they become charged. The other one charges negatively.
But overall they remain electrically neutral.
A PVC rod rubbed against leather charges negatively.
An acrylic glass rod rubbed against leather charges negatively.
A PVC rod rubbed against paper charges negatively.
An acrylic glass rod rubbed against paper charges positively.
A PVC rod rubbed against PE foil charges negatively.
An acrylic glass rod rubbed against PE foil charges positively.