In a ladder diagram, what does a normally open contact do when energized?

• A. It closes the circuit and allows current to flow.
• B. It opens the circuit.
• C. It remains unchanged.
• D. It short-circuits.

Answer: (A)

Normally open contacts act like a switch that is open until the controlling input is energized. When that input is energized, the contact closes, completing the path in the rung and allowing current to flow to energize the next element or load. This is why energizing a normally open contact closes the circuit and lets current pass. It doesn’t open the circuit, stay unchanged, or short-circuit.