Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: 2 dielectrics in a parrelle plate capacitor. (i dont need answer just the intuition)

  1. Feb 9, 2010 #1
    question:
    so here is what my problem is. there are two dielectrics between a parallel plate capacitor. distance between the two plates is '2s' and each dielectric is 's' long. each plate has a charge of [tex]\itshape \sigma[/tex] (top being pos. and bottom being neg. and doesn't give an area) how would i go about finding the electric fields in each dielectric.

    i was thinking finding the electric field (using a pillbox, and Gaussian theorem) caused by each plate ONLY to the dielectric touching it. after doing that to each do i have to find what the electric field in each dielectric due to the other dielectric and other plate? or am i done there?
    it makes sense that i would have to keep going, but then again, i haven't learned enough from my textbook (Griffith EM 2nd edit.) to continue on with the problem. or i might
     
    Last edited: Feb 9, 2010
  2. jcsd
  3. Feb 10, 2010 #2
    Re: 2 dielectrics in a parrelle plate capacitor. (i dont need answer just the intuiti

    I think I remember the problem you are talking about , (Griffith textbook is a great one but I aslo struggled with the probelms he wrote) ..

    anyway, I suggest you start from the fact that : integral of D .da = Q(fenc) ,and find D from there , then you can easily find E using :

    D = e E (e here is epsilon) ..

    I hope I was able to help you with this problem .. :)
     
  4. Feb 10, 2010 #3
    Re: 2 dielectrics in a parrelle plate capacitor. (i dont need answer just the intuiti

    ok, ya that's what i was going for, but do u know if each dielectric is effected by just the plate touching it, or everything including the other dielectric?
     
  5. Feb 11, 2010 #4
    Re: 2 dielectrics in a parrelle plate capacitor. (i dont need answer just the intuiti

    when you find D you should notice that it is the same for both dielctric, so in order to find E you just need to find (epsilon) for each one then from there you can get E .. Do you agree with that? If it is still not clear ask again ..
     
  6. Feb 11, 2010 #5
    Re: 2 dielectrics in a parrelle plate capacitor. (i dont need answer just the intuiti

    ya im pretty sure i get the intuition behind it, ill take it that i just use Gaussian pillbox for each of the dielectrics that it touches and see where that takes me
     
  7. Feb 11, 2010 #6
    Re: 2 dielectrics in a parrelle plate capacitor. (i dont need answer just the intuiti

    I believe you are starting in the right way, try to solve it and let us know what answer you will end up :) ..
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook