Surface integral

  • #1
636
2

Homework Statement


This is not a HW prob. Just a question.
When doing surface integrals, why should the area element ds be dotted with the normal. I don't get it .
[tex]\oint[/tex]A.n ds

Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
gabbagabbahey
Homework Helper
Gold Member
5,002
7

Homework Statement


This is not a HW prob. Just a question.
When doing surface integrals, why should the area element ds be dotted with the normal. I don't get it .
[tex]\oint[/tex]A.n ds

It doesn't have to be, in general. There are other types of surface integrals as well. The type you've listed above is designed to determine the flux of the vector field A through the surface you are integrating over. The dot product is there because, by definition of flux, you are only concerned with the component of A that is perpendicular to the surface at each point on the surface.
 
  • #3
636
2
Ok. Thanks. I can live with it now.
 

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