Integrating n.curl F and n^grad(phi) on a Closed Surface

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The discussion focuses on proving that the integrals of n.curlF ds and n^grad(phi) ds over a closed surface equal zero. Participants confirm the use of identities such as div curl F = 0 and discuss Stokes' Theorem, which relates the integral of a differential form over a volume to the integral over its boundary. The integrands' divergences are analyzed, leading to the conclusion that both integrals are indeed zero due to established vector calculus identities.

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  • Familiarity with the divergence and curl operations in vector fields.
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Tiggy
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I am trying to show for a closed surface
the integral n.curlF ds and
the integral n^grad(phi) ds
both equal zero.

Any ideas? Do I need to use identities such as div curl F=0
I can't seem to find a way to make the integrands equal zero.

Thanks
 
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does ^ mean a cross product? If that is the case, then what do you mean by the integral of a vector being equal to zero? Do you mean the vector (0,0,0)?
 
Siberius, I assume dS is actually a vector too, Tiggy just didn't put in the 'dot' to make it a scalar.

Tiggy, Stokes Theorem is that for a nice surface/volume you have the relation

[tex]\int_{V}d\eta = \int_{\partial V}\eta[/tex]

You're asking to find [tex]\int_{S = \partial V}\eta[/tex] where [tex]\eta[/tex] is the integrands you've given. Can you work out their divergences? The first one is quite clearly zero by the identity you mention. The second one is zero by the fact [tex]a.(b \times a) = 0[/tex], even when [tex]a = \nabla[/tex] (proof by suffix notation).
 

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