Calculating Integrals with Gauss's Theorem

In summary, the Gauss theorem states that the flux through a closed surface S is equal to the volume integral of the divergence of the vector field A over the enclosed volume V, taking into account any discontinuities in the vector field within the region. This can be expressed as \int_S \vec{A}\cdot\vec{dS}= \int_V div \vec{A}dV. However, for regions where A is not differentiable, the surface S' must be subtracted from the integral to account for this discontinuity.
  • #1
matematikuvol
192
0
[tex]\oint_S \vec{A}\cdot d\vec{S}=\int_V div\vec{A}dv[/tex]

Suppose region where [tex]\vec{A}(\vec{r})[/tex] is diferentiable everywhere except in region which is given in the picture. Around this region is surface [tex]S'[/tex]. In this case Gauss theorem leads us to

[tex]\int_S \vec{A}\cdot d\vec{S}+\int_S \vec{A}\cdot d\vec{S}=\int_{V'} divAdv[/tex]

Am I right?
 
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  • #2
Here is the picture
 

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  • #3
Well, what you wrote is not correct because you have "S" on both integrals and I suspect you want "S' " on one. But even then it not correct- you need to subtract not add:
[tex]\int_S \vec{A}\cdot\vec{dS}- \int_{S'} \vec{A}\cdot\vec{dS}= \int_V div \vec{A}dV[/tex]
 

What is Gauss's Theorem?

Gauss's Theorem, also known as the Divergence Theorem, is a mathematical concept that relates the surface integral of a vector field over a closed surface to the triple integral of the divergence of the same vector field over the volume enclosed by that surface.

How is Gauss's Theorem used to calculate integrals?

Gauss's Theorem can be used to convert a difficult surface integral into an easier triple integral, or vice versa. It allows for the calculation of integrals over a closed surface by instead integrating the divergence of the vector field over the volume enclosed by that surface.

What are some common applications of Gauss's Theorem?

Gauss's Theorem has many applications in physics and engineering, specifically in the study of electric and magnetic fields. It is used to calculate the electric flux and magnetic flux through closed surfaces, which is important in understanding the behavior of these fields.

Are there any limitations to using Gauss's Theorem?

Yes, Gauss's Theorem can only be applied to closed surfaces. It also assumes that the vector field being integrated is continuous and has a continuous derivative within the volume enclosed by the surface.

Can Gauss's Theorem be extended to higher dimensions?

Yes, Gauss's Theorem can be extended to higher dimensions using the generalized Stokes' Theorem. This allows for the calculation of integrals over higher dimensional surfaces by instead integrating the divergence of the vector field over the higher dimensional volume enclosed by that surface.

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