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Homework Help: Charging an airplane

  1. Jan 28, 2004 #1
    AN airplane is flying through a cloud. The airplane is at 2100M and the top height of the cloud is 4100M @ 23 C. The bottem of the cloud is 500m @-47 C. What is the strength of the electric field E at the aircraft.

    Now I broke it up into to parts, for the top of the cloud and the bottem.

    Top of the cloud:

    Using coulumbs law: 8.98755 x 10^9* 23/ 4100-2100) = 1.03357e8

    Bottem of the cloud:

    8.98775 x 10^9 * 47/ 2100-500 = 2.64009e9

    I added both of those up and i submited my answer and it said it was wrong. Can anyone aid me?
  2. jcsd
  3. Jan 28, 2004 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The distance should be squared.

    Also, make sure you put your parentheses in the right place. I assume that you are actually typing the numbers into your calculator correctly, but just be careful.

    8.98775 * 10^9 * 47 / 2100 - 500

    is not the same as

    (8.98775 * 10^9 * 47) / (2100 - 500)

    - Warren
  4. Jan 28, 2004 #3

    Doc Al

    User Avatar

    Staff: Mentor

    Assuming that the charged clouds can be treated as point sources of the electric field: use [itex]E=\frac{kq}{r^2}[/itex]. (You forgot to square your distances.)
  5. Jan 28, 2004 #4
    crap..... wow i'm so retarded thanks alot doc
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