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What's the shape of a microwave beam?

  1. Feb 20, 2008 #1
    What's the shape of a microwave beam in a microwave oven? I wonder wether is a ray a small cone, a big cone a band...

    Does this beam reflects on the inner walls of the microwave or get absorbed? I would say the second one because one side of the food, if it doesn't turn inside the microwave, doesn't get warm.

    Thank you.
  2. jcsd
  3. Feb 20, 2008 #2


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    The entire cavity of the microwave is resonant, so the EM field effectively fills the entire space with a standing wave.

    In much the same way, a flute can fill a room with a standing wave of a steady note, but it cannot be said that the sound leaves the flute in any particular direction or with any particular "beam" shape.

    - Warren
  4. Feb 20, 2008 #3
    Thanks for answering but i thin'k you're someway wrong. Food get hot in very different intensities in different parts if it doesn't turn, and because of that, there is a turning plate. (And i'm talking about homogeneous food).

    Actually there is another curious effect. The part touching the plate gets hot very much quickly that the "free" part. I'm thinking of a steak, but happens with other things.
  5. Feb 20, 2008 #4


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    Think again. Look at an example of a standing wave. There are regions where there are nodes in the wave, meaning no oscillation or energy at that location in space.

  6. Feb 20, 2008 #5


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    And the purpose of the rotation would be to run the food through each of those anti-nodes? (And of course prevent superheating)
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