Recreational Vehicle (RV) Technician Practice Test

What must be true when measuring the current in a circuit?

1. The circuit must be open

2. The power must be turned on

3. The multimeter must be set to resistance

4. All switches must be off

The correct answer is: The power must be turned on

When measuring current in a circuit, it is essential that the power is turned on. This is because current flow is only present when there is voltage supplied to the circuit; therefore, if the power is off, the circuit will not allow any current to flow, and the measurement would not provide any useful information. Setting the multimeter appropriately for current measurements, which typically requires measuring current in series with the circuit, is fundamental to an accurate reading. Using the resistance setting, for example, would not allow for current measurement but rather measure how much opposition the circuit offers to the flow of current, which is not relevant when you are specifically looking to measure current. For the circuit being open, this would not be suitable as the current would cease to flow when the circuit is not complete. Likewise, having all switches off would similarly prevent any current from flowing, making the measurement impossible. Therefore, having the power on is crucial to obtaining a valid current reading.