Is the Surface Integral Equivalent to the Traditional Definition?

Click For Summary
SUMMARY

The discussion centers on the equivalence of the Surface Integral and the traditional definition of integrals in vector calculus. The user presents definitions for both Line and Surface Integrals, attempting to equate them through the use of position vectors and differential elements. However, it is established that the Surface Integral, defined as ∫∫_S &vec;f ⋅ d&vec{r}, is fundamentally different from the traditional definition ∫∫_S &vec;f ⋅ &hat{n} dS, as they represent different types of integrals—single and double, respectively. The discussion highlights the importance of understanding these distinctions and references Stokes' Theorem as a connecting principle.

PREREQUISITES
  • Understanding of vector calculus concepts, including Line and Surface Integrals.
  • Familiarity with Stokes' Theorem and its applications.
  • Knowledge of differential forms and their notation.
  • Basic proficiency in mathematical notation and integrals.
NEXT STEPS
  • Study Stokes' Theorem and its implications in vector calculus.
  • Learn about differential forms and their role in integrals.
  • Explore the properties and applications of Line Integrals in physics.
  • Investigate the geometric interpretations of Surface Integrals.
USEFUL FOR

Students and professionals in mathematics, physics, and engineering who seek to deepen their understanding of vector calculus and the relationships between different types of integrals.

Jhenrique
Messages
676
Reaction score
4
Hello!

The definition of Line Integral can be this:
\int_s\vec{f}\cdot d\vec{r}=\int_s(f_1dx+f_2dy+f_3dz)

And the definition of Surface Integral can be this:
\int\int_S(f_1dydz+f_2dzdx+f_3dxdy)

However, in actually:
\\dx=dy\wedge dz \\dy=dz\wedge dx \\dz=dx\wedge dy
What do the Surface Integral be equal to:
\int\int_S(f_1dy\wedge dz+f_2dz\wedge dx+f_3dx\wedge dy)=\int\int_S(f_1dx+f_2dy+f_3dz)=\int\int_S\vec{f}\cdot d\vec{r}

I know, I know... I know that, generally, the definition to Integral Surface is:
\int\int_S\vec{f}\cdot \hat{n}\;dS
I until like this definition when compared to its respective Line Integral:
\int_s\vec{f}\cdot \hat{t}\;ds

But, is correct to definite the Surface Integral as:
\int\int_S\vec{f}\cdot d\vec{r}
being
d\vec{r}=(dx,dy,dz)
?
 
Physics news on Phys.org
No, the surface integral is, as you say, a double integral while the path integral is a single integral. They are NOT the same thing. They can, of course, be connected by, for example, the Stoke's Theorem that says that the integral of the curl of \vec{F} over a surface is the same as the integral of \vec{F} around the boundary of the surface.
 
But I definited the Surface Integral with a double integral (as you can see below or above)
\int\int_S\vec{f}\cdot d\vec{r}
with the only difference that I used the position vector r, like in Line Integral. But, second the identities above, to define the Surface integral with ·dr is equivalent to traditional definition, with ·ndS. Correct!?
 
Jhenrique said:
the Surface integral with ·dr is equivalent to traditional definition, with ·ndS. Correct!?

what? your definitions make no sense. ``dx = dy \wedge dz'' is literally nonsensical.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 2 ·
Replies
2
Views
1K