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Homework Help: Find potential energy of cloud

  1. Jun 4, 2010 #1
    1. The problem statement, all variables and given/known data

    Assuming the maximum electric field sustained by dry air in a cloud is 3x10^6 Vm^-1
    And a distanceof 1000 meters between earth and cloud. The cloud is 4km long and 1 km wide. ausume uniform eletric field. Find the potential difference.

    2. Relevant equations
    [itex]\mu = \frac{1}{2}(\epsilon_{0}\times E^2)[/itex]

    3. The attempt at a solution

    [itex]\mu = \frac{1}{2}(\epsilon_{0}\times E^2)[/itex]
    [itex]3\times 10^6 = \frac{1}{2}(8.85\times 10^-12\times E^2)[/itex]
    [itex]E=\sqrt{\frac{3\times 10^6}{\frac{1}{2}(8.85\times10^-12\timesE^2)}}[/itex]
    [itex]E = 8.23\times10^8[/itex]

    using [itex]V=Ed [/itex]
    [itex]E = 8.23\times10^8 \times 1000[/itex]
    =8.23x10^11 volts

    is this right?
    Last edited: Jun 4, 2010
  2. jcsd
  3. Jun 4, 2010 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    You don't need the second formula (which is for the energy stored in an electric field, I believe. The first equation, along with the given information, should be enough to solve the problem.

    Why have you plugged in the value of the electric field, E, for mu? The electric field, E, is already given to you. You don't need to solve for it.
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