Microwaves work by making water molecules in food vibrate. This heats up the molecules by transferring kinetic energy into heat energy.  Light coloured metal walls in a microwave oven reflect the waves, and the turnatable ensures that even heating takes place. Microwaves can’t go through metal but they can go through glass and plastic. This is also why the window in the door contains a metal grid. If these microwaves came outside the oven they would be extremely dangerous.

The microwaves that mobile phone handsets use are much lower strength (they could not be used to pop corn) but scientists are undecided at the moment just exactly what the effects of long term mobile phone use could be. Advice is to keep calls to a miniumum, and to change ears frequently. There is also a lot of concern about the positioning of mobile phone masts, which enable you to get a signal on your phone. These emit a lot more radiation than your phone does.

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