Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which device is used to indicate the existence of a positive or negative charge?

1. Ampermeter

2. Voltmeter

3. Electroscope

4. Galvanometer

The correct answer is: Electroscope

The correct choice is the electroscope, which is specifically designed to detect and indicate the presence of electric charge. An electroscope operates on the principle of electrostatic induction and utilizes metal rods or leaves that respond to an electric charge. When a charged object is brought near the electroscope, the charge causes the leaves or the indicator to either diverge or collapse, visually demonstrating the presence and type of electric charge. In contrast, an ammeter measures the flow of electric current, a voltmeter measures the electric potential difference between two points, and a galvanometer indicates small electric currents or voltage but is not primarily used to detect the existence of charge. Thus, while all of these devices are important in the realm of electricity, the electroscope uniquely serves the purpose of showing the existence and nature of charge.