What is Magnetostatic: Definition and 21 Discussions

Magnetostatics is the study of magnetic fields in systems where the currents are steady (not changing with time). It is the magnetic analogue of electrostatics, where the charges are stationary. The magnetization need not be static; the equations of magnetostatics can be used to predict fast magnetic switching events that occur on time scales of nanoseconds or less. Magnetostatics is even a good approximation when the currents are not static — as long as the currents do not alternate rapidly. Magnetostatics is widely used in applications of micromagnetics such as models of magnetic storage devices as in computer memory. Magnetostatic focussing can be achieved either by a permanent magnet or by passing current through a coil of wire whose axis coincides with the beam axis.

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1. I Why Does the Negative Sign Appear in the Vector Potential Equation?

We have motivated the derivation of the vector potential in the following way: However, I cannot understand where the ##-## sign in the second equality came from. I thought that it was because the gradient was with respect to the ##y##-variable, and then using the product rule one could...
2. Magnetic field at origin due to infinite wires and semicircular turn

Right now, I am trying to calculate the field due to the left straight wire. For clearance, I have oriented the contraption such that the straight wires go from ##z = 0## to ##z = \infty## and pass through ##x = \pm R##, i.e. the semicircle is below the ##x##-axis. The current starts at ##z =...
3. A diamagnetic sphere in a uniform magnetic field

Problem: Solution part a) where formula 6.14 is just M x n. We need to do part b without seperation of variables, I'm quite stuck. Will B just be the magnetic field inside a solenoid? How can I find the other fields.
4. B Virtual photons as force carriers

(My multipart question is from a very naive perspective, so sorry if it is rife with misunderstandings. Please answer conceptually, with as few & as simple equations as possible. I think that all of the answers to these questions should be understandable to a high schooler, though maybe the...
5. I Is the scalar magnetic Potential the sum of #V_{in}# and ##V_{out}##

Hi, I'm wondering if I have an expression for the scalar magnetic potential (V_in) and (V_out) inside and outside a magnetic cylinder and the potential is continue everywhere, which mean ##V^1 - V^2 = 0## at the boundary. Does it means that ##V^1 - V^2 = V_{in} - V_{out} = 0## ?
6. What is the origin of magnetic potential energy?

Recently I have encountered the following expression for the potential energy of a magnetic dipole of moment ##\boldsymbol{\mu}## placed in an external magnetostatic field B: $$U=-\boldsymbol{\mu} \cdot \textbf{B}$$. However, I was told that magnetic fields are non-conservative, so we can't...
7. Magnetostatic question: about electromagnet/permanent magnet

General Information: A coil that is wound on a magnetic core is placed in between two permanent magnets as depicted below. The coil is fixed and the magnets are affixed to a shaft and can rotate freely. Assume that there is 0 friction for the purpose of the following questions Note: arrows on...
8. Help with 3axis Helmholtz Coil

First of all, hello to all of you. My question is, I want to simulate 3-axis Helholtz Coil in Maxwell 3d. I made some models of it, but I am not sure I got all right - especially ration of coils in x-y-z and their current excitation. Second, i'd like to see H field, or B field plot if some of...
9. Magnetic field in an offset hole in a conductor cylinder

Homework Statement A long (infinite) wire (cylindrical conductor of radius R, whose axis coincides with the z axis carries a uniformly distributed current I in the +z direction. A cylindrical hole is drilled out of the conductor, parallel to the z axis, (see figure above for geometry). The...
10. Non Uniform Magnetostatic fields

Homework Statement Describe semiquantitatively the motion of an electron under the presence of a constant electric field in the x direction, E =E0x^ and a space varying magnetic field given by B = B0 a(x + z)x^ + B0 [1 + a(x - z)]z^ where Eo, Bo, and a are...
11. Magnetostatic simulation in ansys maxwell

i am doing a project on effect of high voltage transmission on human. here, i am facing problem in assigning current excitation to power cable in ansys maxwell. whenever i assign current excitation i get an error message " no conduction path found". please, someone help me in this matter.
12. Magnetostatic field calculations

Homework Statement Current, I, flows around symmetrical loop of thin wire. The loop comprises 2 halves (semicircle & triangle). Distance from vertex of triangle equals radius, a, of the semicircle. Find the mag' field at axis of loop (where axes coss) Homework Equations Could I use...
13. Magnetostatic Spin Wave: Wave Modulation in Ferromagnetic Medium

In the context of electromagnetic wave propagation in ferromagnetic medium, what is meant by magnetostatic spin wave? This terminology one came across in the wave modulation in ferromagnetic medium. Thanks in well advance..
14. Question about magnetostatic boundary condition.

My understanding of: \int_S \nabla X \vec{H} \cdot d\vec{S} = \int_C \vec{H} \cdot d \vec{l} = I Means the current I creates the magnetic field in the form of \nabla X \vec{H} instead of magnetic field creates the current I. But in the boundary condition, it claims the tangential...
15. Magnetostatic field: solution to Poisson's equation and Boundary Conditions

How to derive boundary conditions for interfaces between ferromagnetic material and air? Please see the attached figure. Any hints will be greatly appreciated!
16. Expressing magnetostatic equation as a partial differential equation

Hi, I am trying to model the magnetic field from two permanent magnets using Matlab, although my particular problem here relates to the physics/maths involved (though if someone could also give me advice on how to implement this particular problem in Matlab that would be awesome!). My system...
17. Build arbitrary magnetostatic field with dipoles?

By "static" in this thread, I mean the charge and current density is constant in time (so things can be moving, but the distribution cannot). We can build an arbitrary eletrostatic field with a "eletric monopole" density. Since Del.B=0, can we build an arbitrary magnetostatic field with just...
18. Difference in potential induced by a magnetostatic field? O_o

Hi, Why is there a difference in electric potential from a point on the surface of a stationary magnet to a point on a conductor that is placed underneath a dielectric? I placed some stationary magnets on top of glass or a piece of paper and put some aluminum under it, and touch one end of a...
19. New to Maxwell & FEM: Magnetostatic Analysis for Solenoid Valve

Dear all, I'm a new user to Maxwell and to FEM. I am trying to do a magnetostatic analysis for a solenoid valve for finding inductance and force on the armature. I am facing few problems while making the simulation. 1. what value shall I assign for the source? (In the tutorial provided by...
20. Boundary conditions on magnetostatic

Hi I'm trying to solve a magnetostatic problem and I'm not sure which boundary conditions must be applied to the magnetic vector potential (A) on magnetostatic problems? Thanks in advance.
21. Magnetostatic Problems: Calculating Inductance and Loop Internal Inductance

1) Calculate the self-inductance of a coaxial cable of inner radius a and outer radius b. The inner conductor is made of an inhomogenous material having u = 2u0/(1+r) Answer : u0L/8pie + u0L/pie (ln(b/a) - ln((1+b)/(1+a))) 2) Two #10 copper wires(2.588 mm in diameter) are placed parallel...