Besides heat, all electrical circuits radiate something else—electromagnetic fields. Every flow of electrical energy sets up an electromagnetic field that radiates away. Radio and television stations push kilowatts of energy through their antennae so that this energy (accompanied by programming in the form of modulation) radiates over the countryside, eventually to be hauled in by a radio or television set for your enjoyment or disgruntlement.

The electrical circuits inside all computers work the same way but on a smaller scale. The circuit board traces act as antennae and radiate electromagnetic energy whenever the computer is turned on. When the thinking gets intense, so does the radiation.

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