Performance Standards for Microwave and Radio Frequency Emitting Products This webpage provides the standards for microwave emitting devices, including microwave ovens. The Health Physics Society is a group of scientists that research and make recommendations about ionizing and non-ionizing radiation topics. They also produce informational reports, fact sheets, and websites to help people better understand radiation.
The Society is established in the United States as an independent nonprofit scientific organization, and is not affiliated with any government, industrial organization or private entity. Microwave Oven Q and A This webpage shows answers to frequently asked questions about microwave oven use and radiation.
Skip to main content. Contact Us. Radiation Facts. Microwave ovens use electromagnetic radiation. Microwaves do not make food radioactive. Contact Us to ask a question, provide feedback, or report a problem.
Because the radiation from microwaves is non-ionising, it can only cause molecules in the food to move. This is good! In other words, microwave radiation cannot alter the chemical structure of food components. More precisely, when heating food in a microwave, the radiation that the microwave produces is actually absorbed by the water molecules in the food.
This energy causes the water molecules to vibrate, generating heat through this harmless friction, which cooks the food. This mechanism is what makes microwaves much faster at heating food than other methods. Its energy immediately reaches molecules that are about an inch below the outer surface of the food, whereas heat from other cooking methods moves into food gradually via conduction, like the bottom of a saucepan directly touching a hot hob ring.
You want your food being cooked, not you! Microwaves older than 10 years or with faulty doors should be replaced immediately in order to reduce radiation exposure while you cook. Several studies have been carried out using laboratory animals and in-vitro systems outside of a living organism but few have studied living, human tissue so it is difficult to find causal associations.
In , Peter Valberg reviewed all of the epidemiological studies at the time , which looked at the incidence and distribution of cancer in relation to microwave radiation exposure and tried to determine whether microwaves increased the risk of cancer in humans. He found very little evidence to support a causal relationship between this exposure and disease and, whilst considering what else was known about the mechanism that microwaves use, as well as what had been observed in animal studies, he concluded that microwaves do not cause cancer.
This makes sense because we know that the non-ionising radiation used in microwave ovens is not powerful enough to transfer radiation into food; it can only cause the water molecules to move. Having said that, a study printed in Molecular and Cellular Biology found that microwave radiation exposure did not show any signs of increased cancer risk in Swiss albino mice.
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Watch Now. Take Free Tour. Nutritional Therapy. Sports Nutrition. Weight Loss. Dietary Supplements. Usage of the term "radar" has become so common that it is now a word in and of itself, and can refer to systems that use microwaves or radio waves. A little-known historical fact is that an early radar installation was built atop Kahuku Point on Oahu's northernmost tip. According to the state of Hawaii's website, the station actually detected the first wave of Japanese aircraft on their way to attack Pearl Harbor when the planes were miles kilometers out.
However, because the system had been in operation for only two weeks, it was considered unreliable, and the warning was ignored. Over the course of the war, radar was improved and refined, and it has since become an essential element of national defense and civilian air-traffic control.
Radar has found many other uses, some of which exploit the Doppler effect. An example of the Doppler effect can be demonstrated by an approaching ambulance: As it nears, the sound of the siren seems to rise in pitch, until it wails by.
Then, as it recedes into the distance, the siren seems to lower in pitch. Robert Mayanovic, a professor of physics at Missouri State University, said that Doppler radar, which often employs microwaves, is used for air-traffic control and vehicular speed-limit enforcement. When an object is approaching the antenna, the returning microwaves are compressed and thus have a shorter wavelength and higher frequency.
Conversely, return waves from objects moving away are elongated and have a longer wavelength and lower frequency. By measuring this frequency shift, the speed of an object toward or away from the antenna can be determined. Common applications of this principle include simple motion detectors, radar guns for speed-limit enforcement, radar altimeters and weather radar that can track the 3D motion of water droplets in the atmosphere.
These applications are called active sensing, because microwaves are transmitted, and the reflected signals are received and analyzed. In passive sensing, natural sources of microwaves are observed and analyzed. Many of these observations are conducted by satellites looking either back at the Earth or out into space.
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