# Talk:QB/c19ElectricPotentialField GaussLaw

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Calculating ${\displaystyle \int fdA}$ and ${\displaystyle \int fdV}$ with angular symmetry
Cyndrical: ${\displaystyle dA=2\pi r\,dz;\,dV=dA\,dr}$.  Spherical: ${\displaystyle \int dA=4\pi r^{2},\;dV=4\pi r^{2}\,dr}$