Q. On what principle does a refrigerator work? Ironically, refrigerators keep things cold because of the nature of heat. The Second Law of Thermodynamics essentially states that if a cold object is placed next to a hot object, the cold object will become warmer and the hot object will become cooler. A refrigerator does not cool items by lowering their original temperatures; instead, an evaporating gas called a refrigerant draws heat away, leaving the surrounding area much colder. Refrigerators and air conditioners both work on the principle of cooling through evaporation. A refrigerator consists of two storage compartments - one for frozen items and the other for items requiring refrigeration but not freezing. These compartments are surrounded by a series of heat-exchanging pipes. Near the bottom of the refrigerator unit is a heavy metal device called a compressor. The compressor is powered by an electric motor. More heat-exchanging pipes are coiled...