# how to find vector potential

Find the magnetic vector potential of a finite segment of straight wire carrying a current I. Problem on finding the potential function of a vector field $\mathbf{F}(x,y) = 2 \mathbf{i} + 3 \mathbf{j}$ is a conservative vector field. The current at infinity is zero in this problem, and therefore we can use the expression for in terms of the line integral of the current I. Also find the same for an infinite solenoid with n turns per unit length, a radius of R and current I. (Hint: start from V2A = … In Lectures We Saw How To Find The Vector Potential Of A Straight Current Carrying Wire By Equating The Vector Components Of B To 7 X A. Check that your answer is consistent with eq. The root of the problem lies in the fact that Equation specifies the curl of the vector potential, but leaves the divergence of this vector field completely unspecified. (1) The same methods (see Ch. The vector field V must be a gradient field. The correct answer is magnitude 5.1, angle 79 degrees. However, check that the alleged potential Apply the Pythagorean theorem to find the magnitude. If a vector function is such that then all of the following are true: In magnetostatics, the magnetic field B is solenoidal , and is the curl of the magnetic vector potential: 0. is independent of surface, given the boundary . If the wire is of infinite length, the magnetic vector potential is infinite. Compute the vector potential of this column vector field with respect to the vector [x, y, z]: syms x y z f(x,y,z) = 2*y^3 - 4*x*y; g(x,y,z) = 2*y^2 - 16*z^2+18; h(x,y,z) = -32*x^2 - … (2) Electric potential V is potential energy per charge and magnetic vector potential A can be thought of as momentum per charge. Here is a sketch with many more vectors included that was generated with Mathematica. For a finite length, the potential is given exactly by equation 9.3.4, and, very close to a long wire, the potential is given approximately by equation 9.3.5. In the case of three dimensional vector fields it is almost always better to use Maple, Mathematica, or … In physics, when you break a vector into its parts, those parts are called its components.For example, in the vector (4, 1), the x-axis (horizontal) component is 4, and the y-axis (vertical) component is 1.Typically, a physics problem gives you an angle and a magnitude to define a vector; you have to find the components yourself using a little trigonometry. Because of this, we can write vectors in terms of two points in certain situations. One rationale for the vector potential is that it may be easier to calculate the vector potential than to calculate the magnetic field directly from a given source current geometry. The vector field is defined in all R3, which is simply connected, so F is conservative. As we have learned, the Fundamental Theorem for Line Integrals says that if F is conservative, then calculating has two steps: first, find a potential function for F and, second, calculate where is the endpoint of C and is the starting point. In vector calculus a solenoidal vector field (also known as an incompressible vector field, a divergence-free vector field, or a transverse vector field) is a vector field v with divergence zero at all points in the field: ∇ ⋅ = A common way of expressing this property is to say that the field has no sources or sinks. Finding a Vector Potential By implementing a given integration recipe, a vector potentialfor a given vector field is obtained. The vector potential is defined to be consistent with Ampere's Law and can be expressed in terms of either current i or current density j (the sources of magnetic field). 3) that can be used to find the electric potential V can be used to find each component of the magnetic vector potential A because they obey analogous equations. A = sin ( θ ) r ^ − r θ ^ . This allows the formidable system of equations identified above to be reduced to a single equation which is simpler to solve. Solution Recall that. Find a potential function for it. The function \phi (x,y) can be found by integrating each component of \mathbf {F} (x,y) = \nabla \phi (x,y) = \partial_x \phi (x,y) \ \mathbf {i} + \partial_y \phi (x,y) \ \mathbf {j} and combining the results into a single function \phi. b →F (x,y,z) = 2x→i −2y→j −2x→k F → ( x, y, z) = 2 x i → − 2 y j → − 2 x k → Show Solution. The magnetic vector potential is a vector field that has the useful property that it is able to represent both the electric and magnetic fields as a single field. Since A ⃗ \vec{A} A is in spherical coordinates , use the spherical definition of the curl. Given a conservative vector field ( , )=〈 , ), ( , )〉, a “shortcut”to find a potential function )( , )is to integrate ( , with respect to x, and ( , )with respect to y, and to form the union of the terms in each antiderivative. 0. We need to find a potential function f(x, y, z) that satisfies ∇f = F, i.e., the three conditions ∂f ∂x(x, y, z) = 2xyz3 + yexy ∂f ∂y(x, y, z) = x2z3 + xexy ∂f ∂z(x, y, z) = 3x2yz2 + cosz. Convert the vector given by the coordinates (1.0, 5.0) into magnitude/angle format. Formally, given a vector field v, a vector potential is a vector field A such that = ∇ ×. Find the magnetic field in a region with magnetic vector potential A ⃗ = sin ⁡ (θ) r ^ − r θ ^. If you have a conservative vector field, you will probably be asked to determine the potential function. Finding the scalar potential of a vector field. In various texts this definition takes the forms. of EECS As a result of this gauge equation, we find: ( ) (( )) ( ) 2 2 xx r rr And what a vector field is, is its pretty much a way of visualizing functions that have the same number of dimensions in their input as in their output. potential (V,X) computes the potential of the vector field V with respect to the vector X in Cartesian coordinates. We want to ﬁnd f such that ∇f = F. That is we want to have ∇f = ∂f ∂x i+ ∂f ∂y j+ ∂f ∂z k = 2xyi+(x2 +2yz)j+(y2 +2z)k Vectors with Initial Points at The Origin. (5.35) of Griffiths. Let F be the vector ﬁeld 2xyi + (x2 + 2yz)j + (y2 + 2z)k. Find a potential function for F. One can use the component test to show that F is conservative, but we will skip that step and go directly to ﬁnding the potential. Now let us use equation 9.3.5 together with B = curl A, to see if we can find … We start with the first condition involving ∂f ∂x. 11/14/2004 The Magnetic Vector Potential.doc 4/5 Jim Stiles The Univ. Conservative vector fields and potential functions Because $\mathbf{F}(x,y)$ is conservative, it has a potential function. Plug in the numbers to get 5.1. Find the magnetic vector potential of a finite segment of a straight wire carrying a current I. In vector calculus, a vector potential is a vector field whose curl is a given vector field. If a vector field \mathbf {F} (x,y) is conservative, \mathbf {F} (x,y) = \nabla \phi (x,y) for some function \phi (x,y). Vector Potential Causes the Wave Function to Change Phase The Schrödinger equation for a particle of mass m and charge q reads as − 2 2m (r)+ V = E(r), where V = qφ, with φ standing for the scalar electric potential. S d d ⋅= ⋅ ⋅= ∫ ∫ F Fa C vFa ∇ FW=×∇ , ()∇⋅=B 0 BA=×∇ . Find the Vector Potential A of a infinite cylinder of radius a, with sheet current density of j(r) = k8(r – alê in the regions inside and outside of the cylinder. of Kansas Dept. So here I'm gonna write a function that's got a two dimensional input X and Y, and then its output is going to be a two dimensional vector and each of the components will somehow depend on X and Y. By Steven Holzner . \vec{A} = \sin(\theta)\hat{r} - r\hat{\theta}. This is the function from which conservative vector field ( the gradient ) can be calculated. Conservative Vector Fields and Potential Functions. We can make our prescription unique by adopting a convention that specifies the divergence of the vector potential--such a convention is usually called a gauge condition . Remember that a vector consists of both an initial point and a terminal point. Note the magnetic vector potential A(r) is therefore also a solenoidal vector field. The probability density of ﬁnding the particle at … This is analogous to a scalar potential, which is a scalar field whose gradient is a given vector field..