What type of switch do on-off thermostats utilize?

On-off thermostats utilize an open contact switch, which is central to their function of regulating temperature. When the temperature exceeds a specified setpoint, the thermostat closes the switch, allowing electrical current to flow and triggering the heating or cooling system. Conversely, if the temperature drops below the setpoint, the switch opens, interrupting the current and shutting off the system. This simple mechanism ensures the environment remains at the desired temperature by either activating or deactivating heating or cooling equipment in response to temperature changes.

The other choices do not accurately represent the mechanism used in traditional on-off thermostats. Humidity compensation involves adjustments for humidity levels but is not related to the fundamental on-off switching action. The mention of two or more switches operated in sequence pertains more to complex controls rather than the straightforward operation of a single switch in a basic thermostat. A potentiometer, which allows for variable resistance and continuous adjustment, is not applicable in a system that operates strictly on an on/off basis. Therefore, the selection of an open contact switch aligns perfectly with how on-off thermostats function in maintaining temperature control.