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Electricity formula

  1. Feb 23, 2014 #1
    I want to know what is the diffrences between E=σ/2ε0 & E=σ/ε0
    of course I know we use the first for a very huge page but what about the second formula?
    I saw in some solving of question when we have 2 pages infront of each others we use both of them...
    I want to understand the deep meaning and usage...
    pls tell me simply beacuse my profession english is not good!
    thank u
  2. jcsd
  3. Feb 23, 2014 #2
    The first formula is used for a thin sheet where the field lines split half in each direction. The second formula is used for the surface of a metal where all the field lines are in one side of the surface (outward), and there is no field in the other side (inward).
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