What is the function of an electroscope?

The function of an electroscope is primarily to determine the polarity of charge. An electroscope is a simple device that can detect electric charge and can indicate whether an object is positively or negatively charged. When a charged object is brought near the electroscope, it causes the leaves of the device to either move apart or collapse, depending on the type of charge present. This movement of the leaves helps in identifying the nature of the charge on the object being tested.

In contrast, the other options involve different electrical measurements or functionalities that are not associated with an electroscope. For example, measuring voltage is typically done using a voltmeter, and current measurements require an ammeter. Storing electrical energy is a function associated with capacitors or batteries rather than electroscopes. Each of these devices has specialized roles that do not overlap with the basic function of an electroscope, which remains focused on detecting and determining electric charge.