Which of the following represents a normally closed switch?

A normally closed switch is one that maintains a closed circuit under normal conditions, meaning that the two contacts are touching when the switch is not activated. Therefore, the correct representation of a normally closed switch is when the two contacts are touching at rest, allowing current to flow through the circuit until the switch is activated to open it.

This design is commonly used in safety and control systems where it is advantageous for the circuit to be closed when not actively manipulated. Activating the switch effectively breaks the circuit, stopping the flow of electricity. In different applications, this can provide a fail-safe mechanism since the device remains powered until a deliberate action is taken to deactivate it.

Understanding this concept is essential for effectively working with electric circuits, as familiar switches and their configurations can affect the overall functionality of the system in which they are incorporated.