ARRL Technician Practice Exam

How is an ammeter usually connected to a circuit?

1. In series with the circuit

2. In parallel with the circuit

3. Disconnected from the circuit

4. At the output end of the circuit

The correct answer is: In series with the circuit

An ammeter is designed to measure the current flowing through a circuit, and it is typically connected in series with that circuit. This configuration ensures that all of the current passing through the circuit also flows through the ammeter, allowing it to accurately measure the total current. When an ammeter is connected in series, it becomes part of the current path, so the current that the ammeter reads reflects the actual current flowing through the entire circuit. If an ammeter were connected in parallel, it would bypass most of the circuit, leading to a very high current flow through the ammeter, possibly damaging it and creating a short circuit. Keeping the ammeter disconnected would yield no measurement, and placing it at the output end of the circuit does not guarantee it would measure all the current in cases where there are branches in the circuit. Thus, connecting the ammeter in series is the only method that provides an accurate measurement of current in the circuit.