Does a new MP3 player weigh less when it has no music on it? (Continued)
鈥� An earlier reply in the 5 July issue regarding the weight of an MP3 player is misleading, although I agree with the conclusion.
It implies that data bits are stored by adding or removing electrons from a memory cell, and that these electrons are supplied by a battery. In fact, bits are stored by moving electrons from one part of the memory cell to another, so there is no net gain or loss of electrons in the memory chip. The chip contains the same number of electrons, and thus weighs the same, whether it鈥檚 all 0s, all 1s or full of data.
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Likewise, when a battery supplies an electron from one pole it consumes one at the other. When the battery is flat it contains just as many electrons as when it was fully charged. No electronic devices accumulate electrons; the flow in to the device is always balanced by flow out.
Doug Fenna, Ryde, Isle of Wight, UK
This article appeared in print under the headline 鈥淗eavy metal鈥�