Officer Aptitude Rating (OAR) Test 2025 – 400 Free Practice Questions to Pass the Exam

An ammeter is a device specifically designed to measure the flow of electric current in a circuit, and it is calibrated to provide readings in amperes (A). When connected properly in series within a circuit, the ammeter allows for the direct measurement of current flowing through that circuit at any given moment.

This tool operates based on the principle that the amount of current passing through a known resistance creates a measurable voltage drop, which can then be interpreted as a specific current value. By using an ammeter, one can determine the efficiency and functionality of various electrical components and systems, making it essential for troubleshooting and ensuring proper circuit design.

In contrast, voltage is measured with a voltmeter, resistance with an ohmmeter, and power requires measurements of both current and voltage. Hence, the clear focus of an ammeter on current flow distinctly identifies it as the correct answer to the question.