Which of the following occurs as soon as a heating thermostat is closed?

• A. The temperature in the room immediately decreases.
• B. The thermostat disconnects from the power supply.
• C. An electric circuit is completed, allowing current to flow to the heating element.
• D. The heating system shuts off and stops producing heat.

Answer: (C)

Verified step by step guidance

1. Understand the function of a heating thermostat: it acts as a temperature-sensitive switch that controls the heating system by opening or closing an electric circuit based on the room temperature.
2. When the thermostat is closed, it means the circuit is completed, allowing electric current to flow through the heating element.
3. Recognize that completing the circuit causes the heating element to receive power and start producing heat, rather than shutting off or disconnecting power.
4. Note that the temperature in the room will not immediately decrease; instead, the heating system will work to increase or maintain the temperature.
5. Therefore, the immediate effect of closing the thermostat is the completion of the electric circuit, enabling current flow to the heating element.