A voltmeter connected across the entire powered circuit should read

A voltmeter connected across the entire powered circuit should read

• A. The current in the circuit
• B. The resistance of the circuit
• C. The supply voltage
• D. Zero

Answer: (C)

A voltmeter measures the potential difference between two points, so it is connected in parallel to read the voltage across those points. When you place it across the entire powered circuit, you’re measuring the voltage across the power source itself, so the reading reflects the supply voltage (assuming the meter’s own loading is negligible). It doesn’t read current, which is what an ammeter does, nor does it read resistance, which is determined by an ohmmeter or similar measurement method. A zero reading would occur only if both points were at the same electrical potential, which isn’t the case across a live power source. In short, the meter should read the supply voltage.

A voltmeter measures the potential difference between two points, so it is connected in parallel to read the voltage across those points. When you place it across the entire powered circuit, you’re measuring the voltage across the power source itself, so the reading reflects the supply voltage (assuming the meter’s own loading is negligible). It doesn’t read current, which is what an ammeter does, nor does it read resistance, which is determined by an ohmmeter or similar measurement method. A zero reading would occur only if both points were at the same electrical potential, which isn’t the case across a live power source. In short, the meter should read the supply voltage.