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An interesting question for you all

  1. Feb 4, 2005 #1


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    I put icecream in my microwave for about 20 seconds. When i take it out i notice that it's softest in the centre. However, when i defrost a loaf of bread it's always softest on the outside and still cold in the centre. Why is this, and if you don't believe me try it!
  2. jcsd
  3. Feb 4, 2005 #2
    I reckon you got those backwards. Bread gets soft on the inside and ice cream on the outside. The first thing to understand is that the main thing microwaves heat up is water. Water is pretty much in every food, so the more there is the faster it will heat up. The waves can easily penetrate the outside of the bread, and on the inside, where it's more MOIST, it causes those molecules to heat up. On the other hand, ice cream is pretty moist all around, so it doesn't penetrate to the center, and the outside gets melted more.

    How a microwave works: http://home.howstuffworks.com/microwave.htm
    Last edited: Feb 4, 2005
  4. Feb 6, 2005 #3


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    no man, I know how a microwave works but this has been puzzling me for ages and I experience it every time i heat up icecream. It's so wierd.
  5. Feb 6, 2005 #4

    Besides water, it also heats sugars and fats.

    Also Ion, there is a way that you can check the speed of light using your microwave. Search GOOGLE for "Microwave+speed of light"
  6. Feb 6, 2005 #5
    How old is the microwave?
  7. Feb 7, 2005 #6


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    The microwave is roughly a year old and is 900watts. I think due to the manufacturing process, there is more sugars or fats in the centre of the icecream tub, which causes the strange phenomena!
  8. Feb 7, 2005 #7


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    I would have to guess that every material has some sort of microwave adsorption cross section. This cross section would not depend only on molecular properties but not necessarily bulk density.

    In a material with a low (or small) microwave cross section you will see deeper penetration, this would be indicated by deeper interior warming, and perhaps slower over all warming, if not all of the microwave energy is adsorbed (think plastic plate).

    Material with a high (or large) microwave cross section will adsorb the microwave energy much quicker after it enters the material, here you may well see a skin depth, an outer layer that gets warm quickly while the interior remains cool.

    There is a separate phenomena at work in a microwave. Since the outer layer of the material is continuously exposed to room temperature air, it will generally warm up slower then the interior of the material, which can only conduct energy to other interior points. So in general the interior heats up faster in a microwave then the exterior.
  9. Feb 7, 2005 #8
    Why do you heat up icecream?
  10. Feb 9, 2005 #9
    Melted icecream tastes way better than frozen ice cream!

    Being at room temp releases the flavors! o/
  11. Feb 9, 2005 #10


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    i0n, you have got us curious.
    please take a multimeter ("voltmeter" that can measure ohms resistance)
    and see if there is signif difference between surface resistance of
    loaf of bread straight from freezer, and container of icecream

    maybe the loaf of bread is covered with a layer of frost
    that is conductive
    and the frost melts and dampens the crust

    maybe the frost on the bread is more crystalline ice (bigger crystals)
    and the icecream has only small crystals because emulsified and thoroughly blended to smoothness

    It beats me. I cannot think why the core of the bread will not heat while the icecream does

    do you heat the icecream in its cardboard container or out in the open on a dish
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