How Do They Work: Microwave Ovens

How does it work? Find out exactly how your microwave oven does it's thing.

It has become an essential kitchen appliance. More often than not, we use it simply to heat up our food, even though it has far more potential than that. But, just how does the microwave oven do its job? Well, to understand the mysteries of the microwave oven one has to first come to terms with the microwave itself. So, lets go to it.

Microwaves are a form of electromagnetic energy, or radiation. According to the electromagnetic spectrum, microwaves fall between infrared rays and radio waves. Microwaves are non ionising energy, which means that they do not have sufficient strength to dislodge electrons from atoms. This makes them far safer than ionising energy, which damages the cells of living tissue. Microwaves, then, have been seen as a safe form of energy and man has subsequently utilised their beneficial aspects.

Microwaves were first used by man in the radars that were developed prior to the Second World War. Today microwaves are used in such varied things as broadcasting, surveillance, cell phones, airport scanners and, of course, the domestic microwave oven.

Microwaves are used to cook food in your microwave oven by the fact that, although the microwaves are reflected by metals, they are absorbed by foods. So, a metal box - the microwave oven - reflects the beams of microwaves, which bounce around inside the oven until they hit the food. Then they are absorbed by the food. This causes the moisture molecules in the food to vibrate rapidly. In fact, the vibration is at the rate of two and a half billion times each second. This friction results in heat and it is this heat that does the cooking. In effect, then, the food is cooking itself.

The great advantage of the microwave oven is that very little of the heat is wasted in heating up the oven or the air within it. In addition, heat is not wasted on heating up the cooking container. This is because the container in a microwave oven simply allows the microwaves to pass through it, neither absorbing nor reflecting them. As a result of these advantages the cooking time of a microwave oven is much quicker than that of a conventional oven. A baked potato, for example, might take 45 to 60 minutes to cook in a conventional oven. With a microwave, however, the same result can be achieved in just two to six minutes.

Microwave ovens were first made available to the public in 1967. In that first year, however, just 10,000 units left the showroom floor. Since then sales have skyrocketed. Today it is a rare thing to see a kitchen that is without a microwave oven. That being the case, just how safe is this commonplace appliance?



In the mid 1970's extensive research was undertaken as to the potential risks involved in exposure to low level microwave radiation. As a result, in the United States the allowable level of leakage of a microwave oven was set at 1,000 microwatts per square centimetre at a distance of five centimeters and 5,000 microwatts per square centimeter thereafter. The only way to know if your microwave oven is leaking radiation within these specified levels is to have it checked by an authorised serviceman.

There is still debate, however, as to whether the allowable levels of leakage are really safe. Some scientists believe that microwave radiation has a cumulative effect on the body. In other words a low level dose of radiation the first day which in and of itself is not harmful can combine with similar low levels on subsequent days to build up to a dangerous level. It would pay then to follow some simple safety rules when using your microwave oven. Here are five things to keep in mind:

(1) make sure that the door of the microwave is always firmly shut before operating. A door with cracked or faulty latches should not be used.

(2) Frequently wash your microwave oven with water and a mild detergent. Do not use scouring pads or steel wool.

(3) Never operate the oven when it is empty.

(4) Stay at least an arms length from the front of an operating microwave oven. Never look into an operating oven.

(5) Never interfere with an oven door interlock system.

Always treat your microwave oven with respect. Use it sparingly and with common sense and caution and it will prove to be a useful and safe kitchen tool for you.

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