- #1
thedaydreamer
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Homework Statement
Consider two long parallel and oppositely charged thick wires of radius d with their central axes separate by a distance D apart. Obtain an expression for the capacitance per unit length of this pair of wires
Homework Equations
[tex]
\oint \vec{E}\cdot d\vec{a} =\frac{Q_{enc}}{\epsilon_0}
[/tex]
[tex]
Q = VC
[/tex]
[tex]
V\ =\ -\int_0^d E\,dx\ =\ \frac{d\,Q}{\varepsilon\,A}
[/tex]
The Attempt at a Solution
I have the solution to this problem. It goes like this:A problem P is considered at A distance r from the axis of the wire. Using Gauss's Law, the electric field at P is calculated and the the electric field due to the other wire is also calculated and then added. What I don't understand is which Gaussian surface is to be considered when calculating the field. Please help.