The ammeter measures what aspect of an electrical circuit?

The ammeter is a device specifically designed to measure the electrical current flowing through a circuit. It quantifies the flow of electric charge, which is typically expressed in units called amperes (or amps). When you connect an ammeter in series with a circuit, it allows you to see how much current is being used by the components in that circuit at any given moment. This is crucial for understanding the performance and efficiency of electrical devices.

The other options, while related to electrical concepts, do not reflect the primary function of an ammeter. Hertz measures frequency, ohms denote resistance, and differences in current is somewhat vague and doesn't specify the measurement being taken. The ability to measure electrical current directly is why the ammeter is an essential tool in electrical engineering and troubleshooting.