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Homework Help: Capacitors, Capacitance and Dielectrics

  1. Sep 7, 2012 #1

    So I am learning about parallel-plate capacitors.

    The way my book puts it is that it is basically two parallel plates of opposite polarities, separated by a distance d. In order to establish that distance, work must be done and the energy is stored as electric potential energy.

    From that description, I understand that the purpose of a capacitor is to store potential energy.

    I then learn that a dielectric can increase the capacitance of a capacitor by decreasing the potential difference but, in the process, it diminishes the stored potential energy, according to the equation:

    Energy = Q2/C

    Why, then, is a dielectric used if it decreases the potential energy (what I thought as the function of the capacitor)? The purpose of a capacitor is to store more charge? There must be a connection I am not seeing. :redface:

    Can anyone elucidate me?

  2. jcsd
  3. Sep 7, 2012 #2


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