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: Capacitance equation help

  1. Aug 15, 2008 #1
    1. The problem statement, all variables and given/known data

    What will increase the capacitance of a capacitor?

    2. Relevant equations

    V = Ed

    3. The attempt at a solution

    Factors that increase:
    -Decrease in distance
    -Increase in charge
    -Decrease in electric field
    -Increase in area (length and width of the capacitor, but its thickness has no affect)

    Would these be correct, also what about the dielectric constant (k), would increasing it increase capacitance or decrease it?
  2. jcsd
  3. Aug 15, 2008 #2


    User Avatar
    Homework Helper

    Re: Capacitance

    Q = VC is not exactly the right equation to consider. The capacitor is the constant that relates the Charge to Voltage and is not a property of the capacitor per se. If you change the voltage then the charge changes as determined by the C - it is just descriptive of the relationship between Q and V as defined by C..

    On the other hand:

    C = εA/d would be more to the point of the question.

    For more on capacitors read the link - https://www.physicsforums.com/library.php?do=view_item&itemid=112
  4. Aug 15, 2008 #3
    Re: Capacitance

    Hello Gear2d, I am Gear300...
    Its pretty much what LowlyPion said. C = Q/V is somewhat deceptive. If you think about it, a stronger electric field should bring in more charges...and it does. If you decrease the value of E, then you decrease the value of Q. C is the constant, and what you would want is a more stable equation for it (provided by LowlyPion). If you want to further adjust the equation, then C = εA/d = Q/V = Q/(Ed)...Q = εAE...so charge increases with increasing electric field. Increasing the dielectric constant k increases the capacitance. If you want to know how, look for something correlating with a microscopic observation of capacitance and dielectrics.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook