What instrument is used to measure electric current in a circuit?

An ammeter is specifically designed to measure electric current flowing through a circuit. When connected in series with the circuit components, it allows for the direct measurement of the current in amperes. The ammeter works on the principle of generating a small voltage drop that is proportional to the current, allowing it to provide an accurate reading of how much electric charge is passing through it per unit time.

In contrast, a voltmeter is used to measure the voltage across two points in a circuit, which involves ensuring that it is connected in parallel with the circuit elements. An ohmmeter measures resistance and is used to determine how much opposition there is to the flow of electric current in a component, typically connected to the circuit without power. A capacitor is an electronic component used to store electrical energy temporarily and does not function as a measuring instrument for current or voltage.