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Microwave Oven Facts

What Are Microwaves?

Microwaves are a form of electromagnetic radiation. Electromagnetic radiation is the flow of photons through space in the form of electric and magnetic fields. Photons are packages of energy. Microwaves are very short radio waves that travel in an invisible circular motion through the air. Microwaves go faster than television waves but slower than infrared rays (microwaves travel at the speed of light, 186,282 miles per second!). They are stronger than radio frequency waves, but weaker than X-rays. They can pass through glass, ceramic, paper, plastic, and similar materials. They are reflected by metal, aluminum foil and absorbed by food. Microwaves have a positive and negative end in the same way a magnet has a north and a south pole.

Many terms are used in describing electromagnetic waves, such as wavelength, amplitude, cycle and frequency.
Wavelength determines the type of radiation, i.e. radio, X-ray, ultraviolet, visible, infrared, etc.
Amplitude determines the extent of movement measured from the starting point.
Cycle determines the unit of frequency, such as cycles per second, Hertz, Hz, or cycles/second.
Frequency determines the number of occurrences within a given time period (usually 1 second); The number of occurrences of a recurring process per unit of time, i.e. the number of repetitions of cycles per second. Frequency in microwave oven is 2450 MHz. Microwaves have a wavelength of 12 cm, rather than short waves (a few metres), medium waves (hundreds of metres) or long waves (thousands of metres)

First Commercial Microwave Oven made in 1947, cost $5000, about 2 metres tall

Who Invented Microwave Ovens?

In 1946, an engineer named Percy Spencer who worked at the Raytheon Corporation was experimenting with a magnetron tube (a tube which forms microwaves). Later on, he saw that the candy bar in his pocket had melted! This puzzled him so he tried an experiment. This time he put some popcorn kernels beside the magnetron tube and went to the other end of the room. Soon the whole laboratory was full of popping popcorn!
The next morning, a curious colleague came when Spencer placed an egg near the microwaves. They both watched the egg quake and shake. Then the colleague went for a closer look when hot egg yolk was splattered all over his face.
Spencer thought about this for a while. If microwaves can cook an egg, melt a candy bar, and pop popcorn maybe they can cook other foods too!
Next thing you know, he was experimenting with the magnetron tube placed in a metal box, which he also put food in. The microwaves reflected off the metal sides and cooked the food. There you go! The first microwave oven!
When the microwave ovens where better designed, they were a big success in countries that have little gas, for example Japan.

How Microwaves Warm up Food

Microwaves warm up food by making the molecules in the food vibrate at incredible speed. Sometimes the food is vibrated so fast that the food molecules tear and rip. Microwaves are absorbed by food, but the microwaves do not make the food radioactive because they turn into heat the minute they are absorbed by food.

Uses of Microwaves

Microwaves can be used in many ways. Here are some of the ways:
· Detecting speeding cars and motorcycles
· Sending telephone messages
· TV broadcasting
· Curing and drying plywood
· Treating muscle soreness
· Curing resins and rubber
· Raising bread and doughnuts
· Cooking potato chips.

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