My lads and I put together a radio kit last week. It wasn’t too technical and didn’t require any soldering but it did give us an idea of how radio signals are picked up. When we finally tested the device, the first thing that we heard on it was Elvis Presley singing Suspicious Mind. It was a bit eerie, like we had created something from beyond the grave, but we found out later that day that it was Elvis’s birthday and, if he had been alive (which some people think he is), he would have been seventy. This electronic story brings me nicely to this weeks letter.
Dear Ian. Re: Microwave ovens. Who invented them and what prevents microwave energy from escaping through the exhaust vents and the perforations in the door? Are these ovens safe? E.H. Buncrana.
Reply. Micro ‘waves’ should not escape through the small perforations in the door, nor should they get out through the exhaust vents, because of the physical characteristics microwave energy. The small holes in the door allow light waves to pass through, making it possible to see the food cooking inside. Because the frequency of light waves is extremely high, its wavelength is small enough to pass through small holes. On the other hand, micro ‘waves’ are lower in frequency, thus they have a longer wavelength. Therefore, micro ‘waves’ are too large to pass through the small holes in the door and in the exhaust vent openings. To the micro ‘waves’, these small perforations actually represent a solid metal wall that effectively blocks or reflects the ‘waves’ back in the opposite direction. Some companies claim that microwave ovens are safe (usually the manufacturers), other organisations want them taken off of the market. Lets look at the history.
THE HISTORY OF THE MICROWAVE OVEN NUMBER 1
Microwave cooking ovens were originally researched and developed by German scientists to support mobile operations during the invasion of the Soviet Union. After the war, the papers and experimental microwave equipment were transferred to the U.S. War Department and classified for reference and scientific investigation. The Soviet Union also retrieved some of the devices and began an experiment on them separately. In Russia, where most of the research into the biological effects of microwave ovens took place, their use was outlawed back in 1976. It is said that Micro ‘waves’ have also been used in brainwashing exercises for the military.
THE HISTORY OF THE MICROWAVE OVEN NUMBER 2
Way back in 1940, two scientists, Sir John Randall and Dr. H. A. Boot, invented a device called a magnetron to produce microwaves in their lab at England's Birmingham University. The magnetron is a key component to the radar (radio detecting and ranging), which bounced microwaves off the enemy's war machines to detect their presence. After the war, in 1946, a Raytheon company engineer named Dr. Percy Spencer was performing tests on a magnetron tube when he fancied a chocolate bar that was in his pocket. He found only a gooey mess. Doc Spencer was well aware of the fact that the magnetron produced heat, but he did not sense any. He suspected that the magnetron had melted the chocolate, not his body heat. He needed to test his theory that the magnetron was cooking his food so he sent out for a bag of popcorn and placed it in front of the magnetron tube. The popcorn popped all over the floor.
The next morning he tried cooking up some eggs. One of his fellow colleagues was very curious and happened to get a bit too close. The egg blew up in his face (this is said to be where we get the expression egg on your face?). Raytheon set out to make the first microwave oven. Since the magnetrons were used to make radars, they gave it the name Radar Range. Raytheon succeeded in building the oven, but it was very large. After all, the 1940's were not known for miniaturisation of electronics. These Radar Ranges did not sell well. Most were sold to restaurants or to the military.
In 1952,the first home model was introduced to the U.S. at the very low price of just $1295! Surprisingly, they started to sell and the rest is microwave history.
RADIATION IS ALL AROUND US
The rate of radio frequencies and microwave radiation is increasing by about 15% per year. Some frequencies such as mobile phones are giving people cause for concern as these devices are used more and more. Radiation comes in many forms; we love to see the biggest source of radiation to come out, the sun. Microwave ovens get a very bad press, Julie’s Grandmother wouldn’t use an electric oven as she thought that the food tasted funny and some people feel the same way about microwaves
Even if you refuse to use a microwave in the house it is very difficult to go out for a meal and not have some food served up on your plate that has been microwaved. Then there is the added treat of having your raw food irradiated to increase the shelf life even before it has been cooked. It’s a wonder we don’t glow in the dark!
If you want further reading and more stories about microwave energy go to www.create-your-healthy-home.com, http://www.laleva.cc/ and www.gallawa.com
Environmental.
Dear Ian. Re: Microwave ovens. Who invented them and what prevents microwave energy from escaping through the exhaust vents and the perforations in the door? Are these ovens safe? E.H. Buncrana.
Reply. Micro ‘waves’ should not escape through the small perforations in the door, nor should they get out through the exhaust vents, because of the physical characteristics microwave energy. The small holes in the door allow light waves to pass through, making it possible to see the food cooking inside. Because the frequency of light waves is extremely high, its wavelength is small enough to pass through small holes. On the other hand, micro ‘waves’ are lower in frequency, thus they have a longer wavelength. Therefore, micro ‘waves’ are too large to pass through the small holes in the door and in the exhaust vent openings. To the micro ‘waves’, these small perforations actually represent a solid metal wall that effectively blocks or reflects the ‘waves’ back in the opposite direction. Some companies claim that microwave ovens are safe (usually the manufacturers), other organisations want them taken off of the market. Lets look at the history.
THE HISTORY OF THE MICROWAVE OVEN NUMBER 1
Microwave cooking ovens were originally researched and developed by German scientists to support mobile operations during the invasion of the Soviet Union. After the war, the papers and experimental microwave equipment were transferred to the U.S. War Department and classified for reference and scientific investigation. The Soviet Union also retrieved some of the devices and began an experiment on them separately. In Russia, where most of the research into the biological effects of microwave ovens took place, their use was outlawed back in 1976. It is said that Micro ‘waves’ have also been used in brainwashing exercises for the military.
THE HISTORY OF THE MICROWAVE OVEN NUMBER 2
Way back in 1940, two scientists, Sir John Randall and Dr. H. A. Boot, invented a device called a magnetron to produce microwaves in their lab at England's Birmingham University. The magnetron is a key component to the radar (radio detecting and ranging), which bounced microwaves off the enemy's war machines to detect their presence. After the war, in 1946, a Raytheon company engineer named Dr. Percy Spencer was performing tests on a magnetron tube when he fancied a chocolate bar that was in his pocket. He found only a gooey mess. Doc Spencer was well aware of the fact that the magnetron produced heat, but he did not sense any. He suspected that the magnetron had melted the chocolate, not his body heat. He needed to test his theory that the magnetron was cooking his food so he sent out for a bag of popcorn and placed it in front of the magnetron tube. The popcorn popped all over the floor.
The next morning he tried cooking up some eggs. One of his fellow colleagues was very curious and happened to get a bit too close. The egg blew up in his face (this is said to be where we get the expression egg on your face?). Raytheon set out to make the first microwave oven. Since the magnetrons were used to make radars, they gave it the name Radar Range. Raytheon succeeded in building the oven, but it was very large. After all, the 1940's were not known for miniaturisation of electronics. These Radar Ranges did not sell well. Most were sold to restaurants or to the military.
In 1952,the first home model was introduced to the U.S. at the very low price of just $1295! Surprisingly, they started to sell and the rest is microwave history.
RADIATION IS ALL AROUND US
The rate of radio frequencies and microwave radiation is increasing by about 15% per year. Some frequencies such as mobile phones are giving people cause for concern as these devices are used more and more. Radiation comes in many forms; we love to see the biggest source of radiation to come out, the sun. Microwave ovens get a very bad press, Julie’s Grandmother wouldn’t use an electric oven as she thought that the food tasted funny and some people feel the same way about microwaves
Even if you refuse to use a microwave in the house it is very difficult to go out for a meal and not have some food served up on your plate that has been microwaved. Then there is the added treat of having your raw food irradiated to increase the shelf life even before it has been cooked. It’s a wonder we don’t glow in the dark!
If you want further reading and more stories about microwave energy go to www.create-your-healthy-home.com, http://www.laleva.cc/ and www.gallawa.com
Environmental.
No comments:
Post a Comment