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Linear material properties?

  1. Dec 22, 2014 #1
    Hi all,

    I have a general question about material properties.

    We know that the material property value depends on the input level. For example, the permittivity in a dielectric material changes depending on the applied electric field.

    That being said, when we apply an alternating electric field, we receive a linear response while at the same time the electric field is going from 0 to the set amplitude. We go through a range of electric fields values before arriving at the final amplitude, yet we still receive a nice sine wave output which is indicative of a linear response.

    This leads to the obvious conclusion that, for the "linear range" , we get a linear response depending on the amplitude of the input. At the moment, I cannot understand this. I would imagine the response would not be a clean sine wave (for a AC input) because the changing properties due to changing electric field.

    Am I missing something here?
  2. jcsd
  3. Dec 24, 2014 #2


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    You might check handbooks, Giacoletto comes to mind, for the properties which interest you.
  4. Jan 14, 2015 #3
    Is there a frequency dependence?
    i.e. linear response at 10 kHz but nonlinear response at 100 MHz?
    Do you have to worry about capacitance in your experimental set up?
    Is there an amplitude dependence? How high of a set point before you get a nonlinear response?
    If you apply a square wave or a triangle wave in your AC signal, do you get the same response?
    revisit The Drude model.
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