Which device is used to measure current in a circuit?

An ammeter is specifically designed to measure current flowing through a circuit. It is connected in series with the circuit so that the current passes through the meter, allowing it to provide an accurate reading of the current in amperes.

Other devices serve different purposes: a voltmeter measures the voltage across two points in a circuit, an ohmmeter measures resistance, and a wattmeter measures power by taking into account both current and voltage. Each of these meters has a unique function based on the electrical parameters they are designed to measure, which is why the ammeter is the correct choice for measuring current.