An electronic electroscope for determining polarity of charge

Abstract

In this study, we made a simple electronic electroscope called a ‘polarity detector’ which can determine the type of electric charge on any objects. We used the polarity detector in some student experiments in the physics laboratory. For example, when we applied a plastic rod to a piece of fabric made of wool, we could easily determine that the plastic rod was electrified with a negative electrical charge using the polarity detector. Similarly, we could show that a glass rod applied to a piece of silk fabric was electrified with a positive type of charge. However, when we carried out the same experiments with a metal leaf electroscope instead of the polarity detector, in both cases, the leaves of the electroscope were opened and gave the same response for plastic and glass rods. Thus, the electroscope with a metal leaf does not provide an idea of the type of electric charge on plastic or glass rods. Although this tool is made of cheap materials and is very simple, we have seen that it works quite well in the laboratory and contributes to the easy learning of static electricity. Therefore, we think it would be useful to use this simple instrument in the physics laboratory as an aid to metal–leaf electroscopy.