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B Force between capacitor plates

  1. Jun 30, 2016 #1
    What will happen to the force between the capacitor plates (Will increase or decrease or remain constant) if we introduce a dielectric between them?

    As per the answer given the physics text book , the force will remain same? But as per my understanding the force should decrease since electrical field between the plates reduces.
  2. jcsd
  3. Jun 30, 2016 #2

    Paul Colby

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    The surface charge on a plate is given by the normal ##D=\epsilon E## field. The force is the charge times the ##E## field. For the same amount of charge, the ##E## field is reduced since ##\epsilon>1## so the force will go down.
  4. Jun 30, 2016 #3


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    I can suggest that either the answer you have found is 'in the back of the book' and is wrong due to a simple typo or, if there is a worked example, there may be more to the question than you have stated.
    For instance, what is the actual circuit? Is the Capacitor attached to a voltage source or was it charged and then disconnected?
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