What is Magnetic field: Definition and 1000 Discussions
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a magnetic field that varies with location will exert a force on a range of non-magnetic materials by affecting the motion of their outer atomic electrons. Magnetic fields surround magnetized materials, and are created by electric currents such as those used in electromagnets, and by electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, they are described as a map assigning a vector to each point of space or, more precisely—because of the way the magnetic field transforms under mirror reflection—as a field of pseudovectors.
In electromagnetics, the term "magnetic field" is used for two distinct but closely related vector fields denoted by the symbols B and H. In the International System of Units, H, magnetic field strength, is measured in the SI base units of ampere per meter (A/m). B, magnetic flux density, is measured in tesla (in SI base units: kilogram per second2 per ampere), which is equivalent to newton per meter per ampere. H and B differ in how they account for magnetization. In a vacuum, the two fields are related through the vacuum permeability,
B
/
μ
0
=
H
{\displaystyle \mathbf {B} /\mu _{0}=\mathbf {H} }
; but in a magnetized material, the terms differ by the material's magnetization at each point.
Magnetic fields are produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin. Magnetic fields and electric fields are interrelated and are both components of the electromagnetic force, one of the four fundamental forces of nature.
Magnetic fields are used throughout modern technology, particularly in electrical engineering and electromechanics. Rotating magnetic fields are used in both electric motors and generators. The interaction of magnetic fields in electric devices such as transformers is conceptualized and investigated as magnetic circuits. Magnetic forces give information about the charge carriers in a material through the Hall effect. The Earth produces its own magnetic field, which shields the Earth's ozone layer from the solar wind and is important in navigation using a compass.
The Earth's magnetic field is cylindrically symmetric and can be described using cylindrical coordinates, (ρ,z,φ). The components of the magnetic field are given by:
(B_φ) = 0
(B_ρ) = −∂A/∂z,
(B_z) =(1/ρ) * ∂(ρA)/∂ρ.
The vector potential for a dipole field is given by
(A_φ) = (B_e)(ρ) *...
Dear all.
I would like to know the general expression of the ratio of the electric field strength E to the magnetic flux density B. I know E/B = c, where c is the speed of light, for a vacuum, but I want to know if this is stil valid for any material where the electric and magnetic fields are...
Homework Statement
Find the magnetic field at point P.
(P is at the centre of two infinitely long wires, carrying current in opposite direction.
Homework EquationsThe Attempt at a Solution
My guess is that since the current direction is opposite and distance between the point and the wires is...
Homework Statement
In the figures below, a copper wire of circular cross section, A, has been bent into a square loop of side length, c, and arc welded at the seam for electrical continuity. Assume that the resulting square loop has a resistance, R, and a mass, M. The loop is originally held...
Homework Statement
A deuteron nucleus (consisting of one proton and one neutron) has a mass of 3.34x10-27kg and a charge of 1.602x10-19C. The deuteron nucleus travels in a circular path of radius, 6.6mm, in a magnetic field with magnitude of 2.1T.
A) Find the speed of the deuteron nucleus
B)...
I tried to calculted the rotating speed fro a proton from the clasical point of view by using its magnetic moment and the moment of a rotating sphere uniformly charged as example here: https://ocw.mit.edu/courses/physics/8-07-electromagnetism-ii-fall-2012/exams/MIT8_07F12_quizsol2.pdf
It is said...
Today I came across an article (not from a authoritative journal) about "Quantum Navigation".
https://www.wired.com/story/quantum-physicists-found-a-new-safer-way-to-navigate/
It is about a method to do navigation by detecting anomalies in Earth's magnetic field. I tried (and failed) to find a...
I have a thin copper tube of 4.4mm inner diameter (inside a long ionizer plasma cannon) and I want to fill in with hydrogen plasma fully ionized at low temperature (100eV), what is recommended magnetic field to have the ions there without touching tha walls?
The plasma life is about 0.5 seconds
Homework Statement
The figure below shows a small circular loop of wire in the plane of a long, straight wire that carries a steady current I upward. If the loop is moved from distance x_2 to distance x_1 from the straight wire, what will be the direction of the induced current in the loop and...
Homework Statement
A rod with mass of m runs on rails in a magnetic field. The rails are connected with a wire at x = 0
so that the rod and the rails together with this wire form a closed circuit. The distance between the rails is L, and the resistance in the rod is R.
We assume that the...
I am trying to find a way to decrease the force between two magnets by putting a physical barrier in the middle of them. I’ve reasearched and found that Mu metals redirect the flux of the magnetic fields so those two magnets shouldn’t have any noticeable attraction between them. Of course...
I have the first and second orders that I use in a magnetic simulator, but i need the thirth also to do also with magnetic cylinders accordingly paper:
Do anybody have it in any code? I should pass to C++
I do not understand the theory of moment of nuclei
I read here: http://www.sjsu.edu/faculty/watkins/nuclearmoment3.htm that the magnetic moment of Hydrogen is 2.79284734 magnetons = 2.79284734*9.274009994e-24 joules/tesla =2.59e-23 joules/tesla
So if I make to rotate a proton using 150 keV...
I used the following links:
C++ software using elliptics integral at: https://tiggerntatie.github.io/emagnet/offaxis/elliptic_c.htm
And the calculator here: https://tiggerntatie.github.io/emagnet/offaxis/iloopcalculator.htm
I placed some values and obtained Br smaller than Bx, so I do not know...
Homework Statement
What causes electric field? What causes magnetic field?
(I) stationary electric fields
(II) moving electric charges
(III) a changing magnetic field
IV) a current-carrying wire
Homework Equations
E=F/q
B=μI/2πr
E electric field
F elecric force
Q charge
B magnetic field
I...
Homework Statement
An electron moving in the -z direction enters a region that has a uniform magnetic field in the +y direction. When the electron enters this region, what direction will it be deflected in?
Homework Equations
F=qv X B
The Attempt at a Solution
I tried answering this question...
Hi all. I am alluding to the Moving Charge in a Magnetic field problem by quoting an MIT lecture below.
Scott Huges – Lecture
http://web.mit.edu/sahughes/www/8.022/lec10.pdf
Suppose we now examine this situation from the point of view of the charge (the “charge frame”). From the charge’s point...
Hi
Please help me in understanding the kind the magnetic field used in an AC generator. Most of the figures (one shown in attached file) are shown with concave poles. Hence the field has to be radial. In such a field the angle between plane of coil and the magnetic field remains zero all the...
Hi all.
I was wondering if time is dilated whilst traveling in a stable magnetic field that is generated by the object travelling, and if so, does this vary if you reduce or intensify the magnetic field?
Also, what happens if the object is generating two opposing magnetic fields, would...
A few simple questions which I am not sure about, it's about NMR.
First sentence: "A magentic field B0 is applied on a sample, If the applied magnetic field B0 is stronger, the magnetisation of material is greater" . Would you say that sentence is correct? As I understood, magnetization is a...
I think the real magenetic field is sum of the magnetic fields calculated in each cross section of solenoid with various angle and same center axis when i apply Ampere's law. (Imagine the cross section contains a part of center line of the solenoid) Please let me know why we don't do like that. :)
Hello all
It's been a while ,as I read the almost daily news on climate change , some question come up to my mind , dose the ionosphere has any effect on climate change , as we all know now the Earth magnetic field is weakening ,and the temperature is rising ,dose this two variables related to...
My question is related to the chapter 10 of L.Sussknd's book on analytical mechanics named "The theoretical minimum". There he considers dynamics of a charged rotor in magnetic field using Hamiltonian formalism and poisson brackets.
He also introduces a treatment of the same kind for a...
Homework Statement
A particle of charge -q and mass m enterd magnetic field B at A with speed v1 at an angle alpha and leaves the field at C with v2 at angle beta.Then,
a)alpha=beta
b)v1=v2
c)particle remains in the field for time t=(2m(pi-alpha))/qB
d)All of these
Please see image below...
Hello everyone!
I'm in my first year of my bachelor in physics and astrophysics at Leiden University, The Netherlands. We have to perform a small experiment were we use a transducer to measure a logarithmic correlation between two certain quantities. As an example our prof. said you could...
Here's a experiment.
There is a magnetic field vertically downward and a charged particle is kept inside it.
Simple.
Does it experience a force?
Now if we move a speed of 2m/s relative to the frame of rest charged particle. Then it must experience a force right?(Becuz now its velocity is not...
Homework Statement
Consider a spiral of 20 turns with inner radius R and outer radius 2R. If the current is i, find magnetic field at the center of spiral
Homework Equations
From Biot-Savart law-dB=mu(idl)/4pi*x^2
The Attempt at a Solution
Integration seems like a good option. x is...
Hello,
For example, an electric field vector, such as the gradient of the potential, passes in the following way to any coordinate system:$$E = -\triangledown{}V = - \frac{{\partial V}}{{\partial x^i}}g^{ij}e_j$$
But what about a vector of a magnetic field? How would it be expressed in any...
If an electron is moving in a circle in a magnetic field, it produces a magnetic field in accordance to the right hand rule. If a proton is moving in a circle in a magnetic field, would it produce a magnetic field in accordance to the left hand equivalent to the right hand rule.
Homework Statement
I tried to understand the problem b) and c).[/B]
Homework Equations
Faraday's law: ∇xE = - ∂B/∂t
emf ε = Bdv
Force : F =ma, Lorenz's force F=q(vxB) ==> ma = IdB
Power : power of battery = εI, mechanical power of the wire = Fv
The Attempt at a Solution
I think I solved...
Homework Statement
Find the magnitude of the magnetic induction B of a magnetic field generated by a system of thin conductors along which a current i is flowing at a point A(O,R,O), that is the center of a circular conductor of radius R. The ring is in the yz plane.
Homework Equations
[/B]...
Homework Statement
[/B]
I am working on a experiment on finding the Earth's magnetic field strength in Denmark. Using a Galvanometer and a constant power source of 5.1V and slowly adjusting the resistance, I was able to find the changes in angle in relation to the changes of current.
2...
Homework Statement
In the figure, an electron of mass m, charge − e, and low (negligible) speed enters the region between two plates of potential difference V and plate separation d, initially headed directly toward the top plate. A uniform magnetic field of magnitude B is normal to the plane...
https://phys.org/news/2018-08-image-sun-magnetic-field.html#jCp
These fields are generated by the solar wind?
By the sun spinning does it generate another mag field?
Is this a good example of how hot objects loose their coherent magnetic field by misaligned temperature generated ad hoc domains...
If I have a magnetic field describing a closed path it means that this closed path is surrounding a current, right? But if I have no current, is it the displacement current ?
I'm thinking of a magnetic dipole, its magnetic field describes closed paths from its north to south pole, so is there a...
I was solving some problems from a textbook and I found this formula for the radial dependence of the sun's magnetic field, ##B(r) \approx B_{\odot} \Big(\frac{R_{\odot}}{r}\Big)^{1/2}##, where ##B_\odot \approx 0.001T## is the magnetic field strength in the photosphere.
But how can this formula...
Homework Statement
[/B]
I'm stuck on part (b) and (c) of the following question
Homework Equations
The Attempt at a Solution
The partition function was ##Z_N = 2 cosh(μBβ)## where ##β = \frac {1}{kT}##. From there I used ##U = - \frac {∂}{∂β} ln (Z_n)## to get ##U = -NμB tanh( \frac...
Homework Statement
Homework EquationsThe Attempt at a Solution
I know that, according to the right hand rule, the direction of the field lines for X and Z are anti-clockwise and Y is clockwise. What do I do next? Thank you!
Don't know if this is the right place to post this, but it seemed like the best place to start.
I'm wondering how much stronger would the Earth's magnetic field need to be in order to make quantum levitation using Earth's magnetic field alone a possibility.
Bonus: Effects the change in strength...
Homework Statement
I am trying to solve a problem that I have invented.
It consists of a metal stick of mass m, which falls by the action of gravity (g=constant) within a perpendicular constant magnetic field B. The direction of magnetic fiel is showed in the image.
The stick makes electrical...
Hi all,
Not a question about completing homework here, but I'm a teacher looking to create a realistic engineering question for an assignment.
I have an engineering scenario I've set for the assignment which is a junior engineer working for a marine engineering company so all of the questions...
Homework Statement
A proton is projected perpendicularly into a magnetic field that has a magnitude of 0.30 T. The field is then adjusted so that an electron will follow a circular path of the same radius when it is projected perpendicularly into the field with the same velocity that the proton...
Homework Statement
One component of a magnetic field has a magnitude of 0.0431 T and points along the +x axis, while the other component has a magnitude of 0.0686 T and points along the -y axis. A particle carrying a charge of +1.70 × 10-5 C is moving along the +z axis at a speed of 4.24 × 103...
What if an electromagnet's core is on the outside? How would it's magnetic field look? (The wire being wrapped in coils on the inside of a tube or pipe looking metal)
If your fingers of one hand curl around the axis of rotation of the accretion disc of a massive black hole and your fingers point in the direction of the flow is the direction of the central twisted poloidal magnetic field given by a right hand rule, a left hand rule, no rule?
Is there a simple...
Could anyone point me to the proper formula to calculate the magnetic field strength in the gap/hole(ID) of a diametrically magnatized ring magnet.
https://www.skycraftsurplus.com/rp9291magnetdonut17odx08id-1.aspx
Hello! I am confused about the first EM problem on http://web.mit.edu/physics/current/graduate/exams/gen2_F00.pdf (page 4, with the cylinder in a magnetic field). The solution can be found http://web.mit.edu/physics/current/graduate/exams/gen2sol_F00.pdf. In part a the solution is...