Which statement describes an open circuit?

Which statement describes an open circuit?

• A. An open switch prevents current from flowing; the circuit is broken
• B. Current flows freely in all parts
• C. Voltage becomes zero
• D. Resistance disappears

Answer: (A)

An open circuit means the conducting path isn’t complete, so charges can’t form a continuous loop and current can’t flow. The statement that an open switch prevents current from flowing and that the circuit is broken captures this idea perfectly, because the break in the path stops the current even though a voltage source may still be present. Voltage does not have to be zero in an open circuit—the source can maintain a potential difference across the open gap, but no current will flow. And the idea that resistance disappears isn’t accurate; with the circuit open, the effective resistance is very high (infinite), which is why current stops.

An open circuit means the conducting path isn’t complete, so charges can’t form a continuous loop and current can’t flow. The statement that an open switch prevents current from flowing and that the circuit is broken captures this idea perfectly, because the break in the path stops the current even though a voltage source may still be present.

Voltage does not have to be zero in an open circuit—the source can maintain a potential difference across the open gap, but no current will flow. And the idea that resistance disappears isn’t accurate; with the circuit open, the effective resistance is very high (infinite), which is why current stops.