Which electrical device is primarily used to measure current flow?

The correct choice, which is the amperemeter, is specifically designed to measure the flow of electric current in a circuit. This device is essential for understanding the amount of current that is passing through a conductor, allowing electricians and technicians to monitor and ensure that electrical systems are operating within safe and efficient parameters.

An amperemeter typically provides readings in amperes (A), which is the standard unit of electric current. It can be used in various applications, including troubleshooting and assessing the electrical components of a system to ensure proper functionality.

The other devices listed serve different purposes: a voltmeter measures the voltage across a circuit, an ohmmeter measures electrical resistance, and a wattmeter measures power (the product of voltage and current). Each of these tools is crucial in the field of electrical work, but the amperemeter's primary focus on current flow distinctly categorizes it as the appropriate choice for the question asked.