What tool is commonly used for measuring electrical current?

The ammeter is the tool specifically designed for measuring electrical current, which is expressed in amperes. It is capable of providing precise readings of the flow of electric charge within a circuit. When connected correctly in series with the circuit, the ammeter can determine how much current is passing through a conductor, making it essential for tasks that require monitoring and troubleshooting of electrical systems.

While other tools like a voltage tester can assess voltage levels and a multimeter can measure various electrical properties including voltage, resistance, and current, the ammeter is solely focused on current measurement. An insulation resistance tester is intended for evaluating the insulation quality of cables and equipment but does not provide current measurement capability. Thus, the ammeter is the correct choice when specifically asking for a tool used to measure electrical current.