question_answer 24)

                  If a refrigerator's door is kept open, will the room become cool or hot? Explain.                

Answer:

                  No. A refrigerator is a heat engine that operates in the backward direction i.e., it extracts heat from a low temperature reservoir and transfers it to a high temperature reservoir. No refrigerator is completely efficient. Thus, it exhausts more heat into the room than it extracts from it. Obviously, the net effect is to increase the temperature of the room. Thus, a room cannot be cooled by keeping the door of a refrigerator open.