Why do pickles glow when you heat them in a microwave oven?
In conventional chemistry, demonstrations of glowing pickles are familiar to those involved with electrochemistry and science education. By placing a high voltage (typically 110 or 230 volts ac) across electrodes in either end of a pickled cucumber, it can be made to emit a yellowish glow, as the current passes through. The glow is only observed after the pickle has been significantly heated by the electrical current – typically a couple of minutes – which should give the reader some clue as to the mechanism. What is being observed asnot a luminescent glow, but a process of electrical arcing through pockets of vapour in the heated pickle. In the microwave oven, a pickle is likewise subjected to an alternating electric field and currents are induced within it (as with metals ). Dielectric heating effects ensure that the pickle is rapidly heated and, in contrast to its electrically activated counterpart, the pickle begins glowing very soon after the demonstration is started. The microwav
