Used in electrostatic experiments to determine the potential difference between two charged bodies, whether they are positively or negatively charged This instrument is used in electrostatic experiments to measure the potential difference between two charged bodies; Make sure the object is alive; check if the object is active or passive. Check the insulation of the object and test for induction charging. Before use, it is best to wipe the insulating sleeve with a soft dry cloth, because there is often dust and moisture here, which will damage the insulation performance. If the instrument is seriously damp, it is best to wait until it is dry before use.