How Everything Works
How Everything Works How Everything Works

Question 552

Can we add a section to a microwave oven that gets the food or drinks cold? - MH
Not without adding a full-blown refrigerator. While it's relatively easy to add thermal energy to food or drink, it's much harder to remove that thermal energy. Since energy is conserved, the thermal energy that you remove from the food must be transferred elsewhere. Since heat (moving thermal energy) normally flows from a hotter object to a colder object, you must make something colder than the food before the heat will leave the food. While it's possible to cool an object to a temperature lower than its surroundings, this cooling process requires a heat pump, a device that actively pumps heat from a cold object to a hot object (against its natural direction of flow). A refrigerator is such a heat pump.

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