Recreational Vehicle (RV) Technician Practice Test

What is the correct way to connect a voltmeter in a DC circuit to measure current?

1. In parallel with the load

2. In series with the source

3. In series with the load

4. In parallel with the source

The correct answer is: In series with the source

To measure current in a DC circuit, it is essential to connect the voltmeter in a way that allows it to accurately gauge the flow of electric charge. The correct method is to connect the voltmeter in series with the source. This configuration ensures that the entire current flowing through the circuit also passes through the voltmeter, allowing it to measure the current directly. Connecting in series means the current does not need to split or find alternative paths, which would happen if connected in parallel. When a voltmeter is set up correctly in series, it can account for the voltage drop and thus provide an accurate reading of the current flowing through the circuit. In contrast, if a voltmeter is connected in parallel to either the load or the source, it can result in an inaccurate measurement or even damage the voltmeter and the circuit itself. This is because voltmeters are designed to measure voltage, not current; they have high internal resistance, which when connected in parallel could lead to excessive current flow through the voltmeter, potentially destroying the instrument. Therefore, connecting the voltmeter in series with the source is the appropriate method for measuring current in a DC circuit.