Which item is a switch used for momentary contacts, common in control circuits?

• A. Toggles
• B. Microswitches
• C. Rotary Selectors
• D. Rheostats

Answer: (B)

Momentary contact switches close only while the actuator is being operated and return to their original state as soon as release occurs. In control circuits, you want a device that gives a quick, definite signal for a brief moment, and that reliability is a hallmark of a microswitch. Microswitches are small, snap-action devices designed for fast and precise actuation; a brief press or lever movement makes or breaks the circuit, and releasing it restores the prior state. They’re commonly used as limit sensors, door interlocks, or start/stop triggers because of this fast, momentary contact behavior.

Toggles, by contrast, typically stay in their chosen position until moved again, so they aren’t inherently momentary. Rotary selectors require rotation to change the circuit and aren’t defined by momentary contact. Rheostats are variable resistors, not switches, so they don’t provide momentary on/off action.