Which of these measures electrical current in a circuit?

An ammeter is specifically designed to measure electrical current in a circuit. It works by being connected in series within the circuit, allowing it to take a direct measurement of the current flowing through it. The reading on the ammeter indicates the flow of electric charge, which is typically measured in amperes (A).

This device is crucial for understanding the performance and behavior of electrical systems, as it helps in diagnosing issues like overloads and ensuring that circuits operate within safe current limits. The design of the ammeter ensures minimal impact on the overall circuit operation, providing accurate readings while maintaining circuit integrity.

Other instruments, like the voltmeter, ohmmeter, and wattmeter, are designed for different purposes. The voltmeter measures voltage, the ohmmeter measures resistance, and the wattmeter measures power, each playing distinct roles in electrical work and analysis.