What device is used to detect the presence of an electric charge?

The metal leaf electroscope is specifically designed to detect the presence of an electric charge. It operates on the principle of electrostatic induction. When a charged object is brought near the metal leaves of the electroscope, it causes the leaves to spread apart due to the repulsion of like charges; this movement indicates the presence of an electric charge.

This device can determine whether an object is charged and provide a visual representation of that charge, making it a valuable tool for understanding static electricity and the behavior of electric charges.

In contrast, a voltmeter measures voltage (electric potential difference) across two points in a circuit, a galvanometer is used to detect and measure small electric currents, and an ammeter measures the flow of electric current in a circuit. While these devices are important for different aspects of electrical properties, they do not serve the purpose of detecting the presence of an electric charge like the metal leaf electroscope does.