1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Finding capacitence, used C = (EoA)/d, but didn't work!

  1. Oct 9, 2005 #1
    This seems like a plug n' chug problem but i missed it somehow..
    A parallel-plate air-filled capacitor having area 38 cm2 and plate spacing 2.0 mm is charged to a potential difference of 450 V. Find the following values.

    (a) the capacitance
    wrong check mark pF
    (b) the magnitude of the charge on each plate
    nC
    (c) the stored energy
    µJ
    (d) the electric field between the plates
    V/m
    (e) the energy density between the plates
    J/m3

    So i used C = (EoA)/d
    A = .38
    V = 450
    d = .002m
    C = [(8.85e-12)(.38)]/.002
    C = 1.68e-9, but the want it in pF, p is e-12, so i moved the decimal over to amek it 1680pF, but it was still wrong, did i mess up converting it from e-9 to e-12?
     
  2. jcsd
  3. Oct 9, 2005 #2

    Physics Monkey

    User Avatar
    Science Advisor
    Homework Helper

    38 cm^2 = .0038 m^2
     
  4. Oct 9, 2005 #3
    hm...1 meter = 100 centimeters
    38cm/100cm = .38m
     
  5. Oct 9, 2005 #4

    lightgrav

    User Avatar
    Homework Helper

    Area is NOT measured in "cm", but in cm x cm .
    as in 10cm x 3.8 cm ... Convert both of them!
     
  6. Oct 9, 2005 #5
    I know area is m^2, not m, or cm^2, not cm...
    The problem already gives me the Area, so its already cm^2:
    38 cm^2, so i want to conver that into meters, so .38 m^2. 2.0mm is the distance, i don't square that also.
     
  7. Oct 9, 2005 #6

    Physics Monkey

    User Avatar
    Science Advisor
    Homework Helper

    [tex] 38 \, cm^2 = 38 \, cm^2 * \frac{1 \, m}{100 \, cm}* \frac{1 \, m}{100 \, cm} = 38*10^{-4} \, m^2 = .0038 \, m^2 [/tex]
     
  8. Oct 9, 2005 #7
    ohhhh my bad, sorry i'm slow hah, thanks guys!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Finding capacitence, used C = (EoA)/d, but didn't work!
  1. Finding capacitance (Replies: 29)

  2. Finding capacitance (Replies: 8)

Loading...