Used in electrostatic experiments to determine the potential difference between two charged bodies, whether it is charged, positive or negative The instrument is used in an electrostatic experiment to measure the potential difference between two charged bodies; Verify that the object is energized; verify that the power of the object is positive or negative; Inspect the insulation of the object and the test for induction electrification. It is best to wipe the insulating sleeve part with a soft dry cloth before use, because it often has the influence of dust and moisture, which destroys the insulation performance. In the case that the instrument is seriously affected by moisture, it is best to use it after drying.