Replies

1. 
   Guest_ | Jul 30, 2000 10:20pm | #1

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   Sorry I know nothing about microwaves. However a simple test would be to put a dry plate inside and run it for 1 1/2 minutes. If the plate is hot it must be malfuntioning.

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   Guest_ | Jul 30, 2000 10:37pm | #2

   *everything you put in amicrowave gets hot.... some materials are designed to have their molecules excited .. (these are the """microwave-safe"""utensils) some of the plastic utnensils and containers cannot withstand this activity and deform permanently...unless i'm wrong about this .. your cookware will get hot wether or not it has food or water on it or in it... i use the microwave for a platewarmer on occasion....

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   Guest_ | Jul 31, 2000 12:29am | #3

   *not my major area of expertise (don't know if it the area of expertise of anyone on this board) but used to work with some electronics types. mainly microwaves cause certain materials to vibrate, thus get hot. water is best, fat somewhat, glass basically none. to check if it is your container, do this test: put the empty container in the microwave next to a glass of water (also in the microwave). Heat both for 30 sec. if water is hot and container is not, then microwave is fine and container is "microwave safe", meaning microwave energy just passes thru it ("transparent" to microwave light). if container is hot, then it absorbs some microwave energy and shouldn't be used in the microwave (you can, but it will always get hot, and some of your microwave's energy is wasted. a long cooking time could cause it to crack, also). if neither the water or the container get hot, your microwave is broken.most of the time the container gets hot, sometimes very hot, from conduction from the hot food inside, especially with long cooking times or use of a deep container full of food (frowned upon by microwave gurus). You put hot food in any container and the container will get hot eventually.If you're really paranoid, you can get a microwave leakage tester at a Radio Shack or some electrical supply houses (cheap ones can be found at some appliance stores) and make sure all the microwaves are staying inside and not trying to cook you outside.hope this helps. Rich.

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   Guest_ | Jul 31, 2000 03:52am | #4

   *Having taken my microwave apart (to replace the well-buried light bulb that I couldn't live without), I can tell you it's a very simple device with a power supply, timer/control, frequency generator and magnetron (antenna). It generates high-frequency (2.45 gigahertz) microwave radiation, which interacts with different materials according to their opacity to the radiation: water is "translucent," plastic/ceramic/glass nearly transparent, metal (even the door with the little holes) opaque. It's kind of like the way glass allows most visible light through but blocks a significant amount of UV.You have to very careful with oil and fats because they can be heated to extremely high temperatures without boiling or other visible changes -- from hard experience many years ago, let me advise against heating a bagel with cream cheese! I think I remember hearing that running a microwave oven at or near empty may damage the magnetron.I don't know a whole lot, but I am good at looking things up. Check out the endless FAQ at: http://rabi.phys.virginia.edu/HTW//microwave_ovens.htmlIt suggests some inexpensive microwave testers. Apparently the microwave frequency is -not- one of water's resonant frequencies, rather a compromise based on other factors. One question I have is whether a microwave's design 2.45 gHz frequency can drift over time; if so, perhaps there could be strange results such as what you've described.A bit of trivia -- the origin of microwave ovens and incidentally why the first microwave ovens were called "Radaranges":Q: Who invented the microwave oven and how did he think of it?In 1945, American engineer Percy Le Baron Spencer was working with radar equipment at Raytheon and noticed that some candy he had in his pocket had melted. Radar equipment detects objects by bouncing microwaves from them and Spencer realized that it was these microwaves that had heated the candy (as well as his body...oops!). Raytheon soon realized the potential of Spencer's discovery and began to produce the first microwave ovens: Radaranges. These early devices were large and expensive and it wasn't until 1967, when Amana, a subsidiary of Raytheon, produced the first household microwave oven, that microwave ovens became widely available.

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   Guest_ | Jul 31, 2000 07:41pm | #5

   *Andrew,Just a minor correction: Regular glass blocks IR but not much UV. You probably meant to write that anyway.Steve W.

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   Guest_ | Aug 01, 2000 08:28am | #6

   *I have noticed glass blocks noise too. :)

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   Guest_ | Aug 01, 2000 11:50am | #7

   *You said it all in those first 6 words.Glass is not transparent to microwaves.Glass will heat up when put in a microwave with nothing else. There is nothing wrong with a microwave that heats a glass that has nothing in it. It is doing what it was designed to do. Have you ever even tried your own experiment ?I have. Even though I was sure of the results before I did. 3 different microwaves now. Soon to be 4. Same results in all of them. The empty glass is not as hot as the one with water in it. But it does get hot. It also gets hot when it is in there with nothing else at all. Leave the microwave on for 4 minutes, you'll need an oven mitt to remove the glass.

4. 
   Guest_ | Aug 01, 2000 01:11pm | #8

   *I should correct myself here...Glass is not totaly transparent to microwaves. The more pure the glass, the more transparent. But it will still be affected by the microwaves, and get hotter, the more time it is left in them.

5. 
   Guest_ | Aug 02, 2000 04:50am | #10

   *Agreed. The point of the test is to see if the test container is "mostly" transparent, often called "microwave safe". The idea of the water is to have something to absorb the microwave energy, so the empty glass only absorbs as much as the material itself does not allow to pass thru. An empty glass, or even the glass shelf on the bottom of my microwave will get hot since the energy has no where else to go except into heating the glass. The water gives it some where to go, and the 30 seconds keeps things short enough so the glass is not hot, and a non microwave safe plate won't be destroyed or get way too hot.I did the test again for myself just to make sure. With the water, an empty glass beside the full one stayed cool, slightly warm at the thickest parts of the glass. The water was very hot. The identical glass containing the water was also hot, not because of the microwaves heating the glass (since the other one didn't get hot), but because of conduction from the hot water into the glass. The part above the water wasn't very hot, also.I was just trying to show that the glass (Jim's container in the original post) getting hot did not mean the microwave was broken, or that the container was what was absorbing the microwaves. Sorry if I confused the issue. Rich.

2. 
   Jim_Jaarsma | Aug 02, 2000 04:50am | #9

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   I own a microwave oven that is about 15 years old. When I use it to cook food the containers get really hot. I know that the containers will heat as a direct result of radiant heat coming from the cooking food, but I wonder whether this intense heat is a result of some sort of malfunction. I can't tell you whether or not this is a new occurance, just something I've become more aware of lately. Anybody out there who KNOWS about micowaves could really help me out. Thanks, Jim