ARRL Technician Practice Exam

An ammeter is specifically designed to measure electrical current flowing through a circuit. When connected in series with the load, it directly measures the flow of electric charge, typically expressed in amperes (A). The ammeter works by detecting the magnetic field generated by the current and provides a reading on its scale. In contrast, the voltmeter measures electrical potential difference (voltage) across two points in a circuit, while an ohmmeter is used to measure resistance in ohms by determining how much current flows through a resistor when a known voltage is applied. A wattmeter measures electrical power, calculated based on both voltage and current, but does not directly measure the current itself. Therefore, the ammeter is the correct tool for measuring electrical current.