Step 4: Examine the gaussian surface

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[line of charge]

The flux through the endcap 1 is zero since A1 is perpendicular to E everywhere on this surface. Similarly, the flux through surface 3 is zero.

Since the electric field is everywhere constant on surface 2 and points in the same direction as the surface vector at any point, the flux through surface 2 will be the field magnitude E times the area of the tube wall.

Last updated Sept. 25, 1997.
Copyright George Watson, Univ. of Delaware, 1997.