Which component is essential for measuring electrical current in a circuit?

The essential component for measuring electrical current in a circuit is the ammeter. An ammeter is specifically designed to measure the flow of electric current, providing readings in amperes (A). It is connected in series with the circuit, allowing it to take accurate measurements of the current flowing through that particular part of the circuit.

In contrast, a rectifier is used to convert alternating current (AC) to direct current (DC) but does not measure current. A voltmeter measures voltage, which is the difference in electric potential between two points in a circuit, and is connected in parallel. A capacitor stores electrical energy temporarily and is not used for measuring current. Understanding the purpose and function of these components clarifies why the ammeter is the correct choice for measuring electrical current.