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How Does a Microwave Work?

Scholasticus K May 6, 2019
Ever wondered how microwave ovens heat or cook food a bajillion times faster than the good old stove top? Read on to find out about the mechanism of the microwave.

Did you Know?

Cavity magnetrons, the essential components of microwave ovens, were used in Allied microwave radars in the Second World War! This helped the Allies massively, since the Axis powers didn't have the superior microwave technology.
The microwave oven was discovered during the second World War by Dr. Percy LeBaron Spencer, an American engineer who was working on waves that were to be used in radars.
After a particular experiment, Spencer noticed that some of the candies in his pocket had melted while he had been standing in front of a cavity magnetron. This discovery was later on used to make the microwave ovens that have gone on to become an integral part of the modern kitchen.
These stupendously useful devices have made living the modern fast-paced life much easier than it could have been. There are times when an entire day goes by without having to resort to the paleolithic method of lighting a fire in the kitchen.
When we are just too late, too tired, or too lazy to cook, it's this device that we turn to. In order to know how these life-saving microwave oven works, it is first necessary to find out what microwaves are.

What is a Microwave?

Microwaves are a broad spectrum of waves, ranging from the wavelength of 1 millimeter to 1 meter. This puts them between infrared waves and radio waves. The spectra of radio waves, infrared waves and microwaves cross into each other (although infrared waves can be distinguished much easily than the other two).
Microwaves have a higher wavelength, and thus a lower frequency, than visible light, ultraviolet light and X-rays. This means that they are one of the most penetrative of electromagnetic waves.
The low frequency also means that microwaves are non-ionizing waves, i.e., unlike X-rays and gamma rays, they do not cause mutation or cancer if living tissue is exposed to it. However, they can cause microwave burns -- similar to other burns caused due to heat -- if exposed to for even a few seconds.

How Does a Microwave Heat Food?

Microwaves, like other electromagnetic waves, are absorbed by substances such as water and various biological compounds -- for instance, fats. The absorption of microwaves causes molecules to gain energy.
This increases movement of the molecules by a great degree. When an energized molecule collides with another molecule, the extra energy is passed onto the other molecule as heat.
Since the heating process in microwave ovens takes a fraction of the time it would take on a stove top, a majority of nutrients are preserved.

How Does an Oven Produce Microwaves?

The functioning of a microwave oven is actually a quite simple process. The oven takes in electrical energy like any other household gadget, and passes it on to a cavity magnetron.
This is the most important device in the process of the production of microwaves, as it converts electrical energy into microwave radiation, i.e., microwaves. The radiation then goes through a waveguide, through which the waves are directed into the cooking chamber.
Although microwaves can cause burns if tissue is exposed to it, the sophisticated construction of modern ovens guarantees that the radiation doesn't leak and harm the user.
The interlocking switch in the doors of microwave ovens makes sure that the cavity magnetron is not active when the door is open, and the stray microwaves in the cooking chamber are passed off as heat through the oven's exhaust.
Little would Percy Spencer have known when, undoubtedly, he cursed at the sight of the molten chocolate in his trouser pockets, that that accident would spawn one of the most useful gadgets of modern times, the microwave oven.