Integral equation for large surfaces

In summary, the neglect of the terms in a surface integral is due to the assumption that the vector field A goes to zero at infinity at a rate faster than the rate at which the surface grows. Without this assumption, the integral would not necessarily be zero, as seen in the example of a single point charge.
  • #1
Apashanka
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We often neglect the terms of a surface integral ##\int_v(\nabla•A)dv=\int_s(A•ds)## for ##s## to be very large or ##v## to be very large,
What is actually the reason behind this to neglect??
 
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  • #2
The field ##\vec A## is assumed to go to zero at infinity at a rate faster than the rate at which the surface grows.
 
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  • #3
Orodruin said:
The field ##\vec A## is assumed to go to zero at infinity at a rate faster than the rate at which the surface grows.
Okk got it ...thanks @Orodruin
 
  • #4
Orodruin said:
The field ##\vec A## is assumed to go to zero at infinity at a rate faster than the rate at which the surface grows.
But if the rate at which the vector field ##A## goes to zero at infinity is slower than the rate at which the surface grows ,then also it would be zero ,isn't it??
 
  • #5
No. You need the assumption of the field going to zero fast enough. Take the example of the field of a single point charge.
 
  • #6
Orodruin said:
No. You need the assumption of the field going to zero fast enough. Take the example of the field of a single point charge.
Ok the field decreses as ##\frac{1}{r^2}## and the spherical surface element centered at the point charge grows as ##r^2sin\theta d\theta d\phi##
 
  • #7
Apashanka said:
Ok the field decreses as ##\frac{1}{r^2}## and the spherical surface element centered at the point charge grows as ##r^2sin\theta d\theta d\phi##
And so the integral is not zero.
 
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Related to Integral equation for large surfaces

1. What is an integral equation for large surfaces?

An integral equation for large surfaces is a mathematical equation that relates the values of a function on a large surface to the values of the function on a smaller surface. It is commonly used in the field of mathematics and physics to solve problems involving large surfaces, such as finding the electric potential on a conducting surface.

2. How is an integral equation for large surfaces different from other types of equations?

An integral equation for large surfaces is different from other types of equations because it involves integrating a function over a large surface instead of solving for a specific value. This allows for a more general solution that can be applied to a variety of surface shapes and sizes.

3. What are some applications of integral equations for large surfaces?

Some common applications of integral equations for large surfaces include solving problems in electrostatics, heat transfer, and fluid dynamics. They are also used in image processing and computer graphics to model and analyze large surfaces.

4. How are integral equations for large surfaces solved?

Integral equations for large surfaces are typically solved using numerical methods, such as the boundary element method or the method of moments. These methods involve discretizing the surface into smaller elements and then solving the resulting system of equations.

5. What are the limitations of using integral equations for large surfaces?

One limitation of using integral equations for large surfaces is that they can be computationally intensive, especially for complex surfaces. Additionally, they may not provide an exact solution and may require simplifying assumptions to be made. As such, they should be used in conjunction with other methods for more accurate results.

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