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There is an electrical field. There is a line with constant density. We know L (how long is the line). At a distance a from the middle, there is a point. Which is the field there? |dw:1441428125288:dw|
is \(L\gg a\)?
It is not infinite though, so I don't think we can use Gauss here
Actually it does not say anything about the relationship between a and L
i don't know how to deal with the fringing effects the occur at the the end point of the line, i do know how to get the E field if the line if infinite, (good approximation if a<
hmm i maybe if a is a point above the MIDDLE of the line , the fringing effect from both sides cancel
It is in the middle
So I would guess that in horizontal all of them cancel
So I would have to use Gauss?
yeah use this cylinder as your gaussian pill box
Doing that I have E(2pi*a*L) = Qin / epsilon. But they told me doing this was not correct
is Qin the total charge of the line?
i think you have to express the charge in terms of a linear charge density \(\lambda\) \[\lambda = q/L\]
E = lambda/(2 * pi * a * Eo) (Eo is the epsilon)
But still...how would you solve this without Gauss?
you mean like using Coulombs law?
Yep. Coulomb + Electric field
And charge distributions
Found an answer, thanks a lot