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Homework Help: The electric field between infinte plates?

  1. Dec 1, 2011 #1
    Two infinte plates are in the (x,y,z) space. one in X=5 and the second in X=-5. they are charged with superficial density SIGMA. Between them there is a spatial density P. P=A*X^2(X is the variable and A is constant. out the space(for example=X=10 or x=-10) the Electric field is 0.
    I have to find the expression for the field(for every x and x) between the plates. How do I do that?
    The answer is E=(4/3)(∏)K*A(X^3)

    Thanks
     
  2. jcsd
  3. Dec 1, 2011 #2

    Simon Bridge

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    Re: The electricfield between infinte plates?

    Gausses law.
     
  4. Dec 1, 2011 #3
    Re: The electricfield between infinte plates?

    gauss not works here. if i use it, it gives me ...x^2
     
  5. Dec 1, 2011 #4
    Re: The electricfield between infinte plates?

    How do you get [itex]x^2[/itex] when you use Gauss's law? Remember, you have to integrate the charge density. So, what is the integral of [itex]\rho=Ax^2[/itex]? Its definitely not proportional to [itex]x^2[/itex].
     
  6. Dec 1, 2011 #5
    Re: The electricfield between infinte plates?

    thanks! Ive figured out my mistake. its fine
     
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