Induction oven, ferromagnetic

  1. fluidistic

    fluidistic 3,336
    Gold Member

    I do not understand why ferromagnetic materials are more easily heated by an induction oven than a non/low ferromagnetic material such as copper or aluminum.
    Are Eddy currents more easily induced into a ferromagnetic material than a conductor lacking a high ferromagnetic property? Why is it so?
  2. jcsd
  3. An induction cooker for instance creates losses by magnetic hysteresis. It works only with iron pans, not copper.

    Some other induction heaters are designed for other materials, work at other frequencies, and prefer simple conductive material.
  4. fluidistic

    fluidistic 3,336
    Gold Member

    According to wikipedia,
    and they are talking about
    And also
    So this does not seem to be the answer. I'm still clueless as why a ferromagnetic material heats much faster than a non/low ferromagnetic material.
  5. Possible explanations:
    - Wiki botched it. It does happen.
    - Losses result from induced current, but only because the skin effect increases the resistance, and the skin is made much thinner in ferromagnetic materials.
    Why shouldn't you try to put some figures at it? Search for "Kelvin effect". Cookers use high frequencies, like >20kHz.
  6. Ferromagnetic materials switch their internal magnetism back and forth with every switch of the external magnetic field. However the process has hysteresis, that is it is not completely reversible. The internal magnetic domains lag behind the changing external field, so the sweep back and forth describes a hysteresis loop. The larger the area in this loop the greater the loss on each cycle. This loss turns up as heat. Look up 'hysteresis loop' for graphs and further details.

    This effect does not exist in non magnetic materials.
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