What is the relationship between curl and surface integrals in vector calculus?

In summary, The conversation is about finding the derivatives of a vector field in a surface integral equation. The equation shows that the limit of the integral of the surface element d(sigma) divided by the infinitesimal volume element d(tau) is equal to the curl of the vector field V. The person is also asking if there is a way to include images in their message.
  • #1
we are the robots
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Curl and Surface Integral (help!)

Hello people!
I've been working on this problem, but I can't find how differentials of V on the left side of the equation appear.

***
Show, by expansion of the surface integral, that (see attached image).
Hint: choose the volume to be a differential volume, dx dy dz .
***

Here d(sigma) is a vector surface element, V is a vector field, and d(tau) is a infinitesimal volume element.
Well, from the right side of the equation is clear that derivatives of V will appear, but I can't do the same on the left side, where I only get components of the vector field multiplied by infinitesimal area elements.
Using the lower part of the fraction, some of these elements "disappear", but no hint of the derivatives of V appear to me. Any ideas?

By the way, is there any way to put images inside the message?
Thanks!
 

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  • #2
Here's the tex version (faq in general physics forum)

[tex]\lim_{\int d\tau \to 0} \frac{\int_S d\sigma\wedge V}{\int d\tau} = \nabla\wedge V[/tex]

I'm not sure that you really want the limit as the integral of d\tau goes to zero since the integral of d\tau is just the volume (though you've not said what you're integrating d\tau over so I'm guessing here)

Click on the image to see the code for it
 
Last edited:
  • #3


Hello!

Curl and surface integrals are important concepts in vector calculus. Let's break down the problem and try to understand it step by step.

Firstly, let's define what curl and surface integrals are. Curl is a mathematical operator that measures the rotation of a vector field. It is represented by the symbol "∇ x" and is also known as the "cross product". Surface integral, on the other hand, is a type of integral that calculates the flux of a vector field through a surface. It is represented by the symbol "∫∫F⋅d(sigma)" where F is the vector field and d(sigma) is the vector surface element.

Now, let's move on to the problem at hand. The hint suggests choosing the volume to be a differential volume, dx dy dz. This means that we can consider the volume to be a small cube with sides dx, dy, and dz. By expanding the surface integral, we are essentially breaking down the surface into smaller and smaller elements until we reach the infinitesimal element d(sigma).

The left side of the equation represents the curl of the vector field V. To understand how derivatives of V appear on this side, we can use the definition of curl and expand it using the product rule. This will result in the derivatives of V appearing in the equation.

To put images in your message, you can use the "Attach file" button or copy and paste the image directly into the message.

I hope this helps! Keep practicing and you will get the hang of it. Good luck!
 

1. What is the difference between a curl and a surface integral?

A curl measures the circulation or rotation of a vector field at a given point, while a surface integral calculates the flux or flow of a vector field over a closed surface.

2. How are curl and surface integrals related?

The curl of a vector field is used to calculate the surface integral over the boundary of a surface. It represents the amount of circulation or rotation of the vector field through the surface.

3. What is the formula for calculating a curl?

The curl of a vector field F = P(x,y,z)i + Q(x,y,z)j + R(x,y,z)k is given by the cross product of the del operator (∇) and the vector field: curl F = ∇ x F = (∂R/∂y - ∂Q/∂z)i + (∂P/∂z - ∂R/∂x)j + (∂Q/∂x - ∂P/∂y)k.

4. How do you calculate a surface integral?

A surface integral is calculated by taking the dot product of a vector field and a unit normal vector at each point on the surface, and then integrating over the surface. The formula is given by ∫∫S F · dS = ∫∫D F(x,y,z) · n(x,y,z) dA, where F is the vector field, dS is the surface element, and n is the unit normal vector.

5. What is the physical significance of a curl and a surface integral?

A curl represents the amount of rotation or circulation of a vector field, which can have applications in fluid dynamics, electromagnetism, and other areas of physics. A surface integral calculates the amount of flow or flux through a surface, which can be used to calculate quantities such as electric or magnetic flux. Both have important physical implications in understanding and analyzing various systems and phenomena.

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