True or False: To see what the voltage is anywhere in a circuit, you have to compare the voltage at that point to ground.

True or False: To see what the voltage is anywhere in a circuit, you have to compare the voltage at that point to ground.

• A. False
• B. True
• C. Cannot determine
• D. Not applicable

Answer: (B)

Voltage is a potential difference between two points, not an absolute value at a single point. To know the voltage at a specific location, you need a reference point. In most circuits, ground serves as that reference, so measuring the potential of the point relative to ground gives you the node’s voltage. A voltmeter measures the difference between its two leads, so with one lead at the point and the other at ground, you read the voltage with respect to ground. If you chose another reference instead, you’d get the voltage relative to that point, but the common convention is to express node voltages with ground as the reference. That’s why the statement is true.

Voltage is a potential difference between two points, not an absolute value at a single point. To know the voltage at a specific location, you need a reference point. In most circuits, ground serves as that reference, so measuring the potential of the point relative to ground gives you the node’s voltage. A voltmeter measures the difference between its two leads, so with one lead at the point and the other at ground, you read the voltage with respect to ground. If you chose another reference instead, you’d get the voltage relative to that point, but the common convention is to express node voltages with ground as the reference. That’s why the statement is true.