What is Vector fields: Definition and 168 Discussions

In vector calculus and physics, a vector field is an assignment of a vector to each point in a subset of space. For instance, a vector field in the plane can be visualised as a collection of arrows with a given magnitude and direction, each attached to a point in the plane. Vector fields are often used to model, for example, the speed and direction of a moving fluid throughout space, or the strength and direction of some force, such as the magnetic or gravitational force, as it changes from one point to another point.
The elements of differential and integral calculus extend naturally to vector fields. When a vector field represents force, the line integral of a vector field represents the work done by a force moving along a path, and under this interpretation conservation of energy is exhibited as a special case of the fundamental theorem of calculus. Vector fields can usefully be thought of as representing the velocity of a moving flow in space, and this physical intuition leads to notions such as the divergence (which represents the rate of change of volume of a flow) and curl (which represents the rotation of a flow).
In coordinates, a vector field on a domain in n-dimensional Euclidean space can be represented as a vector-valued function that associates an n-tuple of real numbers to each point of the domain. This representation of a vector field depends on the coordinate system, and there is a well-defined transformation law in passing from one coordinate system to the other. Vector fields are often discussed on open subsets of Euclidean space, but also make sense on other subsets such as surfaces, where they associate an arrow tangent to the surface at each point (a tangent vector).
More generally, vector fields are defined on differentiable manifolds, which are spaces that look like Euclidean space on small scales, but may have more complicated structure on larger scales. In this setting, a vector field gives a tangent vector at each point of the manifold (that is, a section of the tangent bundle to the manifold). Vector fields are one kind of tensor field.

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  1. M

    Difference between a conservative and nonconservative vector fields

    From a mathematical standpoint I have no trouble understanding the difference between a conservative vector field and a non-conservative vector field. It's rather simple. The conservative field can be reduced to some functions gradient vector, doesn't care what path you decide to take, and...
  2. W

    Can Vector Fields be Extended to Submanifolds?

    Hi: I am going over Lee's Riemm. mflds, and there is an exercise that asks: Let M<M' (< is subset) be an embedded submanifold. Show that any vector field X on M can be extended to a vector field on M'. Now, I don't know if he means that X can be extended to the _whole_ of M'...
  3. O

    Operations on 2 vector fields?

    Supposing we have as 2 vector fields: F = x^2i + 2zj +3k and G = r^2e_r + 2\cos\Theta e_{\Theta} + 3\sin(2\phi) e_\phi how do i perform the following operations on them? - F\cdot r - F\times r - |G| - G\cdot r
  4. I

    Understanding Field Lines: Exploring Vector Fields

    Homework Statement describe what field lines are (7 marks) Homework Equations The Attempt at a Solution A field line is a locus that is defined by a vector field and a starting location within the field. A vector field defines a direction at all points in space; a field line may...
  5. K

    Potential function for conservative vector fields

    Task: Find a potential function for the conservative vector field (y,x,1) My work: (Df/Dx, Df/Dy and Df/Dz are the partial derivatives) Df/Dx=1, Df/Dy=x, Df/Dz=1 I take the first eq. and integrate, so that I get f(x,y,z) = yx + C I then derivate with respect to y: Df/Dy=...
  6. kakarukeys

    Killing Vector Fields: Generating Local Transformations?

    Can a killing vector field generate a diffeomorphism that only shifts points inside a small part of the manifold and preserves points outside of it? Rotation preserves the metric of a sphere but shifts every points on the sphere, I'd to find out if there is a killing vector field that...
  7. L

    Graphing Vector Fields: How to Determine Grid Size and Plot Vectors?

    What are the general rules that one should use in graphing vector fields. I'm having a lot of trouble doing this and don't really know where to start. If you take F(x,y) = -yi + xj What should be the next step in terms of graphing? They have it drawn in our book as a bunch of vectors...
  8. H

    I have difficulty in visualizing the divergence of vector fields.

    Hi all. I have difficulty in visualizing the concept of divergence of a vector field. While I have some clue in undertanding, in fluid mechanics, that the divergence of velocity represent the net flux of a point, but I find no clue why the divergence of an electric field measures the charge...
  9. F

    Left invariant vector fields of a lie group

    Comment: My question is more of a conceptual 'why do we do this' rather than a technical 'how do we do this.' Homework Statement Given a lie group G parameterized by x_1, ... x_n, give a basis of left-invariant vector fields. Homework Equations We have a basis for the vector fields...
  10. murshid_islam

    Maple Drawing Vector Fields in MAPLE

    i am new in using MAPLE. can anyone please tell me how i can draw a vector field in MAPLE? suppose i want to draw the vector field of \vec{A} = x\hat{i} + y\hat{j}. or you can take any other vector you like to demostrate how i can draw it.
  11. M

    Preplexing Vector Fields

    I am learning vector analysis these days. I have some knowledge of the applications of the vector field in the field of Engineering and Astrophysics. I am also aware of the fact that vector field is a function that assigns a unique vector to each point in two or three dimensional space...
  12. A

    Vector Fields and Vector Bundles

    I need help solving the following problem: Let M,N be differentiable manifolds, and f\in C^\infty(M,N). We say that the fields X\in \mathfrak{X}(M) and Y \in \mathfrak{X}(N) are f-related if and only if f_{*p}(X(p))=Y_{f(p)} for all p\in M. Prove that: (a) X and Y are f-related if and only if...
  13. D

    Noncoordinate basis vector fields

    I'm self-studying Schutz Geometric methods of mathematical physics, having problems with ex. 2.1. page 44. r=cos(theta)x+sin(theta)y theta=-sin(theta)x+cos(theta)y show this is non-coordinate basis, i.e. show commutator non-zero. I try to apply his formula 2.7, assuming...
  14. D

    Noncoordinate basis vector fields

    I'm self-studying Schutz Geometric methods of mathematical physics, having problems with ex. 2.1. page 44. r=cos(theta)x+sin(theta)y theta=-sin(theta)x+cos(theta)y show this is non-coordinate basis, i.e. show commutator non-zero. I try to apply his formula 2.7, assuming...
  15. B

    Line integral and vector fields

    Hi, I'm having trouble with the following question. Q. Let p be a real constant and \mathop F\limits^ \to = \left( {yz^p ,x^p z,xy^p } \right) be a vector field. For what value of p is the line integral \int\limits_{C_2 }^{} {\mathop F\limits^ \to \bullet d\mathop s\limits^ \to } =...
  16. M

    Divergence and solenoidal vector fields

    I want to find which values of n make the vector field \underline{F} = {|\underline{r}|}^n\underline{r} solenoidal. So I have to evaluate the divergence of this vector field I think, then show for which values of n it is zero? Im starting by substituting: \underline{r} = \sqrt{x^2...
  17. B

    Singularities in Conservative Vector Fields: Understanding the Integral Around C

    Suppose we have a conservative vector field on a plane. Suppose also that we have a closed curve C on that plane. Then we have: \int_C \mathbf{F}\cdot d\mathbf{r} = 0 The line integral around C is zero because F is conservative. Here is what I don't understand: If you have one or more...
  18. P

    Uniqueness Theorem's for Vector Fields

    I recall an prof of mine (from a grad EM course) telling me that once the divergence and curl are of a vector field is specified then the vector field is determined up to an additive constant. Helmhotz's Theorem states that any vector field whose divergence and curl vanish at infinity can be...
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