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.
I thought that a nearly parallel entry path would result in a helix of very small, but constant, radius. I would not expect the electrons to focus at a point, but continue along the infinite helix. What have I missed?
Problem Statement: It is possible to describe synchrotron radiation as caused by a loss of electrical charge of relativistic particles that are moving in a magnetic field?
Relevant Equations: E = mc2
An Italian expert of black hole M87 (Elisabetta Liuzzo) explains that the expected axial...
I want to render the Earth’s Magnetic field in a software and simulate solar wind electron interaction with it. How do I calculate the magnetic strength and vector orientation at each point around the Earth up to thousands of km?
Is there a formula?
Or do I need to download a vector field from...
Hi, second problem in one evening, I'm sorry!
But I'm also not quite sure if I did this one right.
I had thought I need lenz's law but there is no current before entering the field so I just use the induced Voltage?
My approach:
## V = \frac {B*A}{t} ##
## IR = \frac {B*A}{t} ## and ## A = v*t...
I went with R=mv/qb, thus -> 6.64e-27*35.6e3/2*1.6e-19*1.8, and got 4.1e-4 m (metres), so diameter is 2R, 8.2e-4 m, as an answer, the reference site gives 3.95e+10 m as the answer, who's right here?
Hi, at this moment I'm trying to figure out one thing. I have a solenoid with a core that has an empty middle, the flux normally loops back around the outside of the solenoid to the other side where it enters back into the core. I need to route this field between the two ends of the solenoid...
Do solar wind electrons turn left and positively charged ions turn right if they are interacting weakly due to long distance with Earth's magnetic field and fail to complete a loop for the electrons that are on the left of Earth and ions on the right? I assume electrons on the right and ions on...
Tried to find the resultant force, but I can't see how the magnetic field affects. I used Faraday's law to find the the diferece of potentials in the plate Wich should be B.d.v, where v is the vertical velocity of plate, but there were not given the resistance or resistivity to relate with the...
a) We can solve for acceleration by looking at FNETy
FNETy = FE (G is negligible)
FNETy = m * a
The mass (m) of an electron is 9.1093836 x 10-31 kg.
The elementary charge (q) of an electron is -1.60217662 x 10-19 C
a = ε * q / m
a = (4.0 x 102 N/C * 1.6022 x 10-19 C) / 9.1094 x...
As I said my goal is to derive the equation ##\tilde{B}^k(\vec{q})=-i\varepsilon^{ijk}q^i\tilde{A}^j_{cl}(\vec{q})##
As far as I know, the magnetic field is defined using the potential as ##\vec{B}=\vec{\nabla}\times\vec{A}##
Then in equation 6.6 they define ##A^\mu(x)=\int...
Problem Statement: Potential difference is the difference in the quantity of charge in both potentials. How does the magnetic field creates this difference of charges ?
Relevant Equations: None
Hi,
I was reading electricity and found that the difference in potential of both end is the...
For the front wire, I got the magnitude of the magnetic field in terms of the magnitude of the magnetic force, the current, "l," and the "theta". I am unsure how to proceed because I thought that the magnetic force is independent of any other forces. I am also just lost in general. Any help...
I started with the first of the relevant equations, replacing the p with the operator -iħ∇ and expanding the squared term to yield:
H = (-ħ^2 / 2m)∇^2 + (iqħ/m)A·∇ + (q^2 / 2m)A^2 + qV
But since A = (1/2)B x r
(iqħ/m)A·∇ = (iqħ / 2m)(r x ∇)·B = -(q / 2m)L·B = -(qB_0 / 2m)L_z
and A^2 =...
All i could think is that the z component of velocity will remain unchnged as there is no force in that direction.And for the x and y component can we imagine the helical motion as a superposition of a circle and a straight line.So for x and y component can we solve for a particle moving in a...
I know that we need to use some boundry condition both on the a radius surface and the b radius surface and somehowuse the superposition on them both, the boundry condition most be for the tangential and the radial part,
the only things I got is that i don`t know how to produce a magnetisation M...
This is a very basic issue but really important as well.
The rectangular loop has length ##l## and width ##h##. I have seen the argument of neglecting the encircled sides of the loop because ##h << 1## while using Ampere's law to calculate the magnetic field flowing over a plane.
I find this...
I read Wikipedia's description of how a plasma ball works. Question: What kind of energy is the "radio-frequency energy from the transformer"? Is in the form of electric field energy, magnetic field energy, or both? Thank you!
(from Wikipedia)...
Although many variations exist, a plasma lamp is...
So, as it says in the title, I am trying to calculate overall voltage induced in a coreless coil in the cases of it being stationary and moving in an alternating magnetic field. To go more into detail, I would like to create a mathematical model of a coil in an alternating magnetic field that...
I tried to look once at the zy axis and saw a two infinite capacitors with fictive charge density of M on the upper plane, and -M in the lower with a distance of h from each other, the two capacitors saparated with d in the y axis,
but when I look in xy axis there was 2 another capcitors the...
$$V = \int \left(\vec{v} \times \vec{B}\right) \bullet \vec{dl} - \int _S \frac{\vec{dB}}{dt} \bullet \vec{ds}$$
From the statement I know that: B⊥v, (B x v) // dl and B // ds.
$$V = \int vBdl - \oint _S \frac{dB}{dt} ds$$
v is the speed with which all the segments dl are aproximating to the...
Assuming that you can create a proton current.
For example, the current of ionized hydrogen is analogous to a conductor.
Question!
Will a magnetic field be created around a conductor with a current of protons?
By analogy with the magnetic field of electrons in a conductor.
v = sqrt( (2 * charge of proton * 3000/e) / (mass of proton))
v = 1.893986024 x 10^`15
r = ( (mass of proton) * (velocity) ) / ((magnetic field) * (charge of proton))
r = 24715769.68 m
Anyone please help
m = 0.005
q = -70 x 10^-6 c
v = 30,000 m/s
Since there is no movement vertically Fb = Mg
So,
q . V . B = mg
So,
(70 x `10^-6) . (30,000) . B = (0.005) . (9.8)
So,
B = 0.0233333 or ~ 23 MT
emf = dΦ/dt = (B*A)*d/dt = B(dA/dt), dA/dt= L*d/dt(vt) = L*v, emf = B*L*v per coil
Since there are 25 loops the total emf= 25(vBL) This is where I'm am stuck. Would I assume that B is 24 uT, the velocity as 3m/s , and the length as 1mm? If so I would get ∆V as 1.8*10^-6.
V=I*R
6v=I*(0.6+0.9)ohms
I=4amp
B=100*(uo)(2N)(I)/L * 1/2 I think since the wire is double wrapped, we multiply the equation by 2, but since we are looking for the magnetic field at the end of the wire we also have to multiply the equation by 1/2
I=4A, uo= 4pi*10^-7
2N/L turns per unit...
F = ma
F = (6x10^-6) * 8
F = 4.8 * 10^-5
F = QBVsin(theta)
F/(BVsin(theta) = Q
(4.8 x 10^-5) / (5 x 10^-3) (4000) (sin(37)) = 3.98 x 10^-6 ~ 4 uc <---- THE RIGHT ANSWER IS -4 uc
Here is a little thought experiment related to magnetism and a perplexing question regarding its physics. Suppose we have a long cylinder of transparent plastic, and we press fit and then cement a circular magnet in one end of the cylinder with its north pole oriented into the cylinder. We also...
Recently I am learning about electrodynamic radiation and its various types, and it occur to me that since the form of the magnetic field created by the dipole radiation is some combination of cos(wt), 1/r, and cos(kr) (take the approximation of r >> c/w)
Therefore, if there is a metal placed...
I'm confused what's meant by a uniform surface current density since this plane has a thickness, It would need a current density distributed through its cross sections, I thought.Edit: I tried solving with proper LaTeX and all my steps, but it looked awful. For outside, I got B=µ_0jd/2.
for...
I am new to the site I apologize If I am posting incorrectly or doing something wrong. I need help figuring out how to increase magnetic field density (gauss/tesla's) extending from a magnetic object's surface, most magnets magnetic density is all in the center. I need this in order to induce a...
Hello,
Let's imagine we have an infinite plane (or large enough compared to the region of interest and measurements) pierced in normal direction by magnetic field B which is uniformly distributed but time varying. For the sake of simplicity we'll presume the magnetic induction is linearly (and...
A charge is entering magnetic field perpendicularly! Griffiths says it motion will be circular! But it is accelerated so it must radiate energy and it's motion should be spiral inward?
I might be a slow learner, but am still trying to understand the difference between field lines and vectors.
I've got that magnetic field lines are symbolic and that the directional arrows applied (from north to south) are a convention.
But see the attached image. The field lines form a closed...
(a) Let's say the loop has fallen ##y## from its initial position. Then the magnetic flux is ##B_{0}w(h-y)## and the induced voltage is ##\mathcal{E}=B_{0}wdy/dt##. Since this voltage is positive, the current flows clockwise.
(b) ##I=\frac{\mathcal{E}}{R}=\frac{B_{0}wv}{R}##
(c) The force on...
for a infinite length length of current, only consider a part of it, is the direction of magnet field of a ring on the mid vertical plane the same magnitude and along the tangential direction? and for a closed surface , if the flux is 0?
I don't understand why a force would be acting on this rectangular coil at all. The magnetic field of the wire would only induce a force on the coil, if the coil had a current flowing through it. At first I would think that the electric field from the varying magnetic field would induce such...
For if the axis of symmetry is oriented along the y-axis I have gotten as far as converting the main integral entirely to cartesian coordinates.
$$\hat{\phi}=-sin(\phi)\hat{x}+cos(\phi)\hat{y} \therefore \hat{\phi} =-sin(tan^{-1}(x/y))\hat{x}+cos(tan^{-1}(x/y))\hat{y}$$...
The question is to find the magnetic field immediately outside a thin hollow cylinder that carries a uniform steady current I on its surface. This is my solution but what I get contradicts amperes law.
So I was able to do out the curl in the i and j direction and got 3xz/r5 and 3yz/r5 as expected. However, when I do out the last curl, I do not get 3z2-3r2. I get the following
\frac{\partial}{\partial x} \frac{x}{(x^2+y^2+z^2)^\frac{3}{2}} = \frac{-2x^2+y^2+z^2}{(x^2+y^2+z^2)^\frac{5}{2}}...
Hello, there are a couple things about magnetism that I do not understand.
1. Why didn't we define the magnetic field to be in the directions of the force? This isn't really a technical question, I am just more curious about why it is this way. The way I was thinking of it, the math seems to...
Hi. In a current carrying conductor because of special relativity amount of protons and electrons differ so we get an electric field or as we call it magnetic field. So if magnetic field is just an electric field how is it that the charge has to move so that magnetic field would exert a force on...
With talk of the Earth's magnetic field slowly moving, (enough to cause navigational issues I've heard) does it effect how the sun's ray hit us? For example, the Northern Lights are solar partials interacts with the magnetic field (I think).
If the poles moves, would it affect the effectiveness...
Hello all,
I have a question with the helix path of proton in a magnetic field that I am a bit stuck on.
Question:
Equations:
F = qv X B
F = mv^2/r
d=vt
My Attempt:
Think the graph drawn is good enough for questions (a). However, I am stuck on (b) and (c).
Firstly I am not entirely sure...
So my thought process is as follows, since the initial centripetal force and the second magnetic force are working together, we can set up an equation to calculating final frequency.
However, I am struggling with how this can be done given so little numbers.
mvi^2/r + qvB = mv^2/r
Am I on the...