PSIA Science Practice Test

The device used to detect and measure electric charge is the electroscope. An electroscope operates based on the principle of electrostatics. It is a simple instrument that consists of a metal rod connected to thin metal leaves or a dial. When an object with an electric charge is brought near the electroscope or touches it, the charge is transferred to the electroscope, causing the leaves to repel each other and spread apart if the charge is of the same kind. This visual separation indicates the presence of electric charge and provides a qualitative measure of its magnitude. The other devices listed serve different functions in the field of electricity. A voltmeter is used to measure the voltage (electric potential difference) across two points in an electric circuit, rather than measuring electric charge itself. An ammeter measures the flow of electric current in a circuit, while an ohmmeter is used to measure resistance. Each of these instruments plays a crucial role in electrical measurements but does not specifically measure electric charge like the electroscope does.