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Electric flux question

  • Thread starter bitrex
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Electric flux question (solved it)

Homework Statement


I have to find the flux of [tex]F = ix + jy + kz[/tex] through three squares, each lying in the xy, xz, and zy planes with sides of length b.

Homework Equations



flux with planar symmetry - E*A.

The Attempt at a Solution



The flux through the square in the x y plane is going to be the z component of the flux function times the area, or [tex]zb^2[/tex]. Similarly the flux through the other 2 surfaces should be [tex]xb^2[/tex] and [tex]yb^2[/tex]. I would think I could sum these to get the total flux through the three surfaces, but the answer turns out to be 0. Ideas would be appreciated.

Edit: The flux through the three squares is zero because they are all perpendicular to the field vector, that is with [tex]\iint \vec{E}\cdot \vec{n} dA[/tex] the normal vector to say, the x y plane is going to be [tex]i0 + j0 + k[/tex] and the field on the xy plane is going to be [tex]ix + jy +k0[/tex]. Same for the other planes. So there's no total flux through the planes because they're always perpendicular to the field vector. No point in doing the integral!
 
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