 
Microwaves are a form of electromagnetic energy that are less energetic than visible light or infrared waves, but have a higher frequency than radio waves. Microwaves aren't just used to cook food in your kitchen. They are also used to visualize weather fronts and storm systems, spot tornadoes, study the Earth from space, and power the GPS signal in your car. Microwave ovens work by using microwaves that are about 12 centimeters in length. Their frequency causes water and fat molecules in food to rotate; this forced rotation of the molecules creates heat, which also spreads to the rest of the food through conduction. Certain types of plastics are able to absorb microwaves, making them prone to melting. Metal reflects microwaves and therefore interferes with the movement of the waves inside the ovens. Satellite communications using microwaves makes the Global Positioning System (GPS) receiver in your car work. Microwaves are able to penetrate the air and clouds in the atmosphere, keeping the signal strong. Doppler Radar used by weather stations and passed on to TV broadcasters shows us weather fronts, lightning and storms by using different microwave frequencies to interact with atmospheric disturbances. Microwaves are beneficial for satellite communication and studying the Earth from space. For example, the ability of microwaves to pass through clouds enables scientists to monitor conditions underneath a hurricane. Microwave astronomy allows us to look at what the universe was like right at its birth. In 1965, scientists at Bell Labs made an incredible discovery by accident: they detected background noise using a special low-noise antenna. The scientists soon realized that they had discovered the cosmic microwave background radiation. This radiation, which fills the entire universe, is radiation left over from its beginning, known as the Big Bang. |