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Homework Help: Dielectric-Dielectric Boundary Conditions

  1. Oct 9, 2011 #1
    1. The problem statement, all variables and given/known data

    No problem, I just have a confusion about a certain concept.

    2. Relevant equations

    3. The attempt at a solution

    I'm confused as to how they draw the result,

    [tex]\oint_{C} \vec{E} \cdot \vec{dl} = E_{1t}\Delta l - E_{2t}\Delta l = 0[/tex]

    You don't really need to do the integration since,

    [tex]\Delta l[/tex]

    is so small. Thus the result must be,

    [tex]E_{net} \Delta l[/tex]

    But why is it such that,

    [tex]E_{net} = E_{1t} - E_{2t}?[/tex]

    It looks as though they are pointing in the same direction in the figure.

    Can someone explain? Am I mixing some things up?

    Thanks again!

    Attached Files:

  2. jcsd
  3. Oct 9, 2011 #2


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    [itex]\vec{\Delta l\phantom{ll}}[/itex] is to the right in one medium, to the left in the other.
  4. Oct 9, 2011 #3

    Thank you.
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