Working Principle of Microwave Ovens
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Read the following passage and please help answer some of the questions below...if possible. :)
A microwave oven uses microwaves to heat food. Microwaves are radio waves. In the case of microwave ovens, the commonly used radio wave frequency is roughly 2,500 megahertz (2.5 gigahertz). Radio waves in this frequency range have an interesting property: they are absorbed by water, fats and sugars. When they are absorbed they are converted directly into atomic motion -- heat. Microwaves in this frequency range have another interesting property: they are not absorbed by most plastics, glass or ceramics. Metal reflects microwaves, which is why metal pans do not work well in a microwave oven.
http://www.howstuffworks.com/microwave.htm/printable
In molecular terms, explain how does the microwave oven cause food to get heated?
John wanted to heat up some frozen instant food. He had forgotten to remove the food from the packaging and moments later he heard a loud sound of plastic bursting open in the oven.Explain why the plastic would burst in the oven
Just need a rough idea on how to work this out. Your help is greatly appreciated
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zz ask pple do your homework? but since I'm bored.
microwave works by reasonace with water molecules.
explode because of expansion of steam/air.
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Originally posted by hisoka:
zz ask pple do your homework? but since I'm bored.
microwave works by reasonace with water molecules.
explode because of expansion of steam/air.
No.I only provided backgrd info for you guys or else it would just be plain questions. Do you think any homework would just give you 2 of these short questions?
Thanks by the way
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Originally posted by Audi:
No.I only provided backgrd info for you guys or else it would just be plain questions. Do you think any homework would just give you 2 of these short questions?
Thanks by the way
Microwaves are electromagnetic waves with a certain frequency.
Water molecules have a natural frequency of vibration similar to that frequency.
Use the concept of frequency resonance to explain what happens to the water molecules when you direct microwaves onto them.
Extrapolate your reasoning to the plastic molecules.
There. Now don't be a lazybum; those should be more than enough tips for you.
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The plastic packaging has a shorter half life than the bombardment of the microwaves, hence causing intergalactic molecular fusion and thus exploded.
