What tool is primarily used to check for continuity in an electrical circuit?

The most appropriate tool for checking continuity in an electrical circuit is the voltmeter or ohmmeter. When you are testing for continuity, you want to determine whether there is a complete path for current to flow. An ohmmeter measures resistance; if the resistance is low (ideally close to zero), it indicates that continuity exists in the circuit.

A voltmeter, while primarily used to measure voltage, can also provide continuity indications when set to a specific scale, typically by showing a value if a circuit is closed. In practical applications, the ohmmeter is commonly used for continuity checks due to its straightforward display of resistance values, making it clear whether a circuit connection is intact.

The other tools mentioned serve different purposes: an amperemeter measures current flow but does not directly test continuity; a capacitor tester focuses on the condition of capacitors; and a frequency counter measures the frequency of signals in a circuit, neither of which are designed for checking continuity directly. Thus, the voltmeter or ohmmeter is the suitable choice for continuity testing in electrical circuits.