Is the statement 'When a circuit is open, voltage does not exist in the circuit' true or false?

• A. True
• B. False
• C. Not sure
• D. Depends

Answer: (B)

Voltage is a measure of potential difference between two points and does not require current to exist. In an open circuit, the path for current is broken, so no current flows, but a source can still establish a voltage between its terminals or across the open gap. For example, with a battery and an open switch, there is the battery’s voltage across the switch even though no current travels through the circuit. A voltmeter placed across the open terminals will read that voltage, demonstrating that voltage can exist without current. If the circuit were closed with a conductor, current would flow and the voltage would then be dropped across the conductor or load according to its resistance. So the statement is not true; voltage can be present even when the circuit is open.