ARRL Technician Practice Exam

What is the correct way to connect a voltmeter to a circuit?

1. In parallel with the circuit

2. In series with the circuit

3. At the ground end of the circuit

4. At the power supply end of the circuit

The correct answer is: In parallel with the circuit

The correct way to connect a voltmeter to a circuit is in parallel with the component or portion of the circuit where voltage is to be measured. When connected in parallel, the voltmeter measures the potential difference (voltage) across the component without significantly altering the circuit's operation. Voltmeters are designed to have a very high internal resistance, which minimizes the current that flows through the voltmeter itself when it's connected. This characteristic allows the voltmeter to accurately measure the voltage without loading down the circuit, which could lead to erroneous readings. Connecting a voltmeter in series would not work to measure voltage as it introduces the voltmeter's resistance into the circuit. This could disrupt the current flow and subsequently provide misleading readings. While considering locations like the ground end or power supply end of the circuit does not provide a definitive method for measuring voltage accurately, they do not represent proper connections for establishing the voltage measurement context needed. Using this proper connection method is crucial for effective troubleshooting and ensuring accurate measurements in electronic circuits.