Microwave Ovens

All sorts of rumors abound about the dangers of microwave ovens leaking and microwaved food being harmful. I think it must be that some people are disturbed because they don’t know what’s going on in the oven and how it works. I hope then that my attempt at explanation is understandable and allays any concerns.

First of all you must know that microwaves are part of the electromagnetic radiation [EMR] spectrum just like radio waves and visible light and x-rays - they are rays of energy that pulse positive, negative, positive, negative, etc. through space and travel at the speed of light.

If the frequency at which the EMR changes from positive to negative is in the visible light region it affects our eyes so we can ‘see’ it as light. When the EMR comes from the sun, the part of it in the microwave region we feel as heat on our skin and think nothing of it. The remote control to turn a TV on and off is in the radio frequency region. X rays are pulses that change positive negative with such high frequency that mostly they pass through the body but the waves are partly absorbed by flesh and bones so give us an ‘x-image' of them.

To understand then how microwaves heat food, you have to know four things:

- 1. Positive is attracted to negative and repulsed by positive – something like the poles of a magnet. - 2. Lots of molecules have charges on them and we’re interested especially in charged water molecules here. - 3. Microwave pulses are slow enough to push and pull charged molecules, like water, around by attractive and repulsive forces as the waves, go past them, just like stick in the water bobs up and down as a wave goes by. - 4. We feel faster moving molecules as heat - the faster they go, the hotter they feel.

So essentially, all microwaves are doing is making charged molecules move faster. Since most plastics and pottery and glass have no charged molecules, they don’t react and stay cool in a microwave oven. Food, on the other hand, mostly has charged water molecules in it and heats up. Actually, microwaving has benefits because, by not heating food too long or too hot, many of the nutrients are preserved!

As far as microwaves leaking out of the oven, unless there is poor seal on the door - as an old, much used oven might have - no microwaves can escape. It’s like a box with a light in it in a dark room, if there are no cracks in the box, no light can escape.

So rest easy – microwave ovens have been around commercially since 1967 and when you look up the hazards, examples have to do with whole eggs in their shells and potatoes with skins intact which tend to explode and splatter because off the pressure of steam formed inside. You can’t heat water to more than 100 degrees C because it then just uses extra heat to form steam - but fats can be heated easily to very high temperatures and splatter so take care in heating them. Otherwise, rest easy – nothing unusual is going on in your microwave oven so just enjoy its wonderful convenience! Rie