What is Magnetic flux density: Definition and 52 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.
In 11.1.3 of Griffith's "Introduction to Electrodynamics 4Ed" appears magnetic dipole radiation, which results in the equation above. According to the resultant equation, there is no magnetic field in the axis of the wire loop because theta=0. However, I think the magnetic flux density is at...
Magnetic flux density(B) is defined as, magnetic force per unit pole strength and flux is defined as magnetic field passing normally through given surface. I think, I am clear about these definitions, and quantitative meaning they carry.
I usually find, in some texts, the definitions as in image...
As stated in the problem, I want to demonstrate mathematically that field line density is directly related to the magnitude of B. How would I be able to do this, other than simply using the flux equation and showing that for a higher flux in the same area, the magnetic field must be rise...
Summary:: Is the magnetic flux density B constant? Is the magnetic flux constant?
I am working on a project design for Uni and I am stuck.
In a magnetic circuit is either the magnetic flux or the magnetic flux density B constant? This magnetic circuit has all different cross section areas and...
I'm trying to understand the relationship between the "number" of field lines passing through a region and the magnetic force in this region.I understand that the drawings are of course conceptual: we cannot draw "all" the field lines (although can be visualized with iron fillings).Also the...
I drew an illustration to make this easier:
Point P is where I wish to find the magnetic flux density H.
Given the Biot-Savart formula:
$$d\textbf{H} = \frac{I}{4\pi}\frac{d\textbf{l}\times\textbf{R}}{R^2}$$
I can let
$$d\textbf{l} = \hat{z}dz$$
and
$$\hat{z}dz\times\textbf{R} =...
While going through an article titled "Reflections in Maxwell's treatise" a misunderstanding popped out at page 227 and 228. Consider the following equations ##(23\ a)## and ##(23\ c)## in the article (avoiding the surface integral):
##\displaystyle \psi_m (\mathbf{r})=-\dfrac{1}{4 \pi} \int_V...
Consider a magnetic dipole distribution in space having magnetization ##\mathbf{M}##. The potential at any point is given by:
##\displaystyle\psi=\dfrac{\mu_0}{4 \pi} \int_{V'} \dfrac{ \rho}{|\mathbf{r}-\mathbf{r'}|} dV' + \dfrac{\mu_0}{4 \pi} \oint_{S'}...
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
In the picture at points A and B are two thin parallel wires, where traveling currents are 15 A and 32 A to opposite directions. The distance between wires is 5.3 cm. Point's P distances from A and B are the same. Calculate the magnetic flux density at point P.
Homework...
Hello all; I am new in this forum, currently in High School.
For some time now, I have been looking online for a relationship between temperature and magnetic flux density of a ferromagnet; below the Curie point. However, I can't seem to find any relationship or formula. Do any of you know...
I am trying to understand the magnetic dipole field via loop of wire.
The above pictures show how this problem is typically setup and how the field lines are typically shown.
The math is messy but every textbook yields the following:
β = ∇xA = (m / (4⋅π⋅R3)) ⋅ (2⋅cos(θ) r + sin(θ) θ)
The...
Homework Statement
Find magnetic flux density B circulation in closed contour. The countour consists of square with a perimeter of 4b. It includes a square conductor with a perimeter of 4a. A homogenic current flows through a conductor with a current density of j.
Homework Equations...
Homework Statement
The magnetic flux density in the vicinity of a large air-cored electromagnet is determined by measuring the induced flow of charge in a small coil as the current in the electromagnet is switched on -- see the diagram below.
Calculate the magnetic flux density at the...
Homework Statement
The diagram shows a uniform magnetic flux density B in the plane of the paper. Q and R mark the points where two long, straight and parallel wires carry the same current, I, in the same direction and perpendicular to the paper. The line through QR is at right angles to the...
Homework Statement
Two identical wires R and S lie parallel in a horizontal plane, their axes being 0.10 m apart. A current of 10 A flows in R in the opposite direction to a current of 30 A in S. Neglecting the effect of the Earth's magnetic flux density calculate the magnitude and state the...
Magnetic flux density B is a vector quantity and thus represents a force. However most texts state that the magnetic force is perpendicular to the direction of B, which is tangential to the magnetic field line at any give point. I assume that this magnetic force refers to the Lorentz force. So...
I decided to simulate this scene in Lord of the Rings for a project in school with the purpose of calculating the "real" mass of the One Ring. I've done the experiments according to this principle sketch but I have some troubles with calculating the magnetic force that the copper coil is...
I am trying to create a solenoid with a high flux density, but I need the specifications (wire gauge, current applied, etc). The diameter of the core would be preferable around 15mm. The length can be pretty much anything reasonable.
I need this for a project that requires a strong repulsive...
Would the direction of the Magnetic Flux Density vector B at the south side be towards the south pole like this?
and is the direction for B correct for the other side?
One more thing, how can magnetic flux density be a vector and have a direction when its sort of a density, I mean its over an...
Hello, all. I have been working on the following problem and was wondering if someone could check my work and provide some valuable input:
Here is my work:
What do you guys think about my approach to this problem?
My reasoning:
The magnetic force on charge q is
Fm = qv x B
B does not change |v|. Therefore, |Fm| is constant at time t > 0 and Fm is always perpendicular to the direction of movement of charge q. Fm behaves as a centripetal force, and thus the charge moves along the circumference of a...
Homework Statement
A long cylinder of radius a with magnetization vector M=M_0*(r/a)^2*a_φ. Find the magnetic flux density inside and outside the cylinder.
Homework Equations
J_m=∇×M
J_ms=M×a_n[/B]
A=(μ_0/4*π)*(∫(J_m/R)dv+∫(J_ms/R)ds)
B=∇×A
The Attempt at a Solution
Basicly what I thought...
We know Total Magnetic Flux B = B_0 + B_m
Where, B_0 is the external field and B_m is the field inside a material.
Now, we get,
B = B_0 + μ_0*M (M is the magnetization)
My question is -
Do I always have to use μ_0 ? If yes then Why?
The material isn't free space, is it?& also
B =...
Hi to all of you,
As the Biot-Savart-Law is based on experimentations in air, i like to know how to calculate the magnetic flux density in material with much greater permeability, where the circular like shape of the field distribution troughout the vicinity does not apply.
Does anyone has a...
Gentlemen, the the image shows 2 N48 neodymium magnets of the same volume 54 in2. On several website I can use magnetic flux density calculators to get the Br of the rectangular magnetic but haven't found one that calculates the value of the arc magnet. The Br value of the rectangular magnet is...
Homework Statement
A solenoid has a radius of 2mm and a length of 1.2cm. If the # of turns per unit length is 200 and the current is 12A, calculate the magnetic flux density at a) the center and b) the ends of the solenoid
Homework Equations
The biot-savart law:
\vec{B} = \frac{\mu_0}{4...
Hello all, long time follower, first time poster.
(Also feel free to move this if it's not in the right section.)
Basically I have this mechanism pictured here:
You can imagine that the drawing is of a top view of a section cut of the total mechanism. This is the radius view, the full diameter...
Im revising for my A levels and I could really do with a simple, straight forward definition for magnetic flux and magnetic flux density. Can anyone please help? I'd be very grateful.
F=BIl
∅=BA
Problem description:
A wery long, than and flat metal plate of width 2a carries the total current I in the z-direction. The current density is uniformely distributed over the metal plate. A point P of particular interest is also shown in the figure, where the point has the position r=ax+ay...
Homework Statement
Calculate the value of magnetic flux density in air in the middle of two straight parallel wires carrying currents of 10A and 20A in the opposite directions. The distance between wires is 10cm.
The Attempt at a Solution
\oint \vec{B}\cdot d\vec{A} = \Phi
\oint \frac{\mu_0...
Homework Statement
A current carrying loop of wire is being monitored using a Hall-effect magnetic field probe placed at its centre. The loop is in air and has a radius of 0.5 m. It is required to monitor the magnetic flux in order to trip the circuit breaker if the current exceeds 100 A...
Hi,
I would like to verify analytically that a vector potential of the form A=1/2(-yB0,xB0,0) produces a constant magnetic flux density of magnitude B0 in the z direction.
(I guess I'd have to use the relation B=\forall\wedgeA...)
Now here is a real world practical application.
Australia Post has a warning for shipping magnetic material in the post. Section D2.9.2 states...
Any material that, when packed, has a magnetic flux density of 0.159 A/m or more at a distance of 2.1 meters from any point on the surface on the...
The magnetic flux density B( in tesla ) inside the solenoid and parallel to its axis is given by the expression
B= permeability of free space x n x I, where n is the number of turns per metre length of the solenoid
my question is so for example, if n = 100turns in 1m and I = 2Ampere...
I have a problem understanding magnetic fieldstrength, magnetic flux, magnetic flux density.
Some questions that answered may ease my understanding:
Is it true that the magnetic field strength B in the core caused by a current in a wire wound on a the same torodial magnetic core is...
[PLAIN]http://img232.imageshack.us/img232/7172/60746674.png
Homework Statement
The picture attached to this question shows a magnetic slab with μr = 50. A thin conducting film (with μr = 1) lies on top of the slab and carries a surface current of 1.0[A/mm] directed out of the page. If...
π²³ ∞ ° → ~ µ ρ σ τ ω ∑ … √ ∫ ≤ ≥ ± ∃ · θ φ ψ Ω α β γ δ ∂ ∆ ∇ ε λ Λ Γ ô
Homework Statement
An arbitrarily long hallow cylindrical electric conductor shown carries a static electric current density J=\hat{z}J0. Determine the magnetic flux density B in the hallow region of radius a. Your result...
A 1mm-diameter copper wire is shaped into a square loop of side = 4cm. It is placed in a plane normal to a magnetic field increasing with time as \vec{B}=1t\hat{z}Wb/m2. Calculate the magnetic flux density at the center of the loop.
I found that the magnitude of the induced current is...
i'm having trouble distinguishing between magnetic flux and magnetic flux density...can someone please explain to me?
also why is it sometimes used interchangeably?
Homework Statement
A current flows in a circular loop consisting of a single turn.If the same wire is bent into a circular loop of 2 turns and the same current is passed through the loop,the magnetic flux density at the centre will change by a factor of ...?
(ans: 4 )
Relevant equations
B...
I would like to put this out for argument that there is no such thing as magnetic flux density. Since magnetism is a wave like on water's surface, it is continuous. Is there a 'water wave density?" I think not. Unless you mean the distance between wave peaks. But flux lines are only arbitrary...
Homework Statement
For my physics investigation I am required to first find the theoretical magnetic flux denisty at different points about a solenoid. The points are outside the solenoid: along the axis but past the ends and; perpendicular to the centre of the solenoid but outside.
So far...
Homework Statement
This is from my textbook Engineering Electromagnetics by John Buck and William Hayt 7th Edn, pg 238 in the chapter titled "The Steady Magnetic Field":
Homework Equations
Divergence theorem:
\oint_S \textbf{B} \cdot d\textbf{S} = \int_{\mbox{vol}} \nabla \cdot...
magnetic flux density is denoted by the B symbol
magnetic flux is denoted by the \phi symbol
so why do people use B as if they were referencing to magnetic flux?
"magnetic flux density is a measurable quantity indicating the strength of a field" ...this was stated by a teacher of...
Homework Statement
Determine the magnetic flux density at a point on the axis of a solenoid with radius b and length L, and with a current I in its N turns of closely wound coil.
Homework Equations
Biot-Savart law: myI/(4pi)integral(dlcross er/R^2) there er is the unit vector in...
hiya
If 'b' is the length of a wire, and 'I' current running trough it, then if put a wire inside magnetic field ( not perpendicullary and also not parallel to magnetic field lines, but some angle in between the two ), then magnetic force on a wire will be:
F = I * b * B * sin[angle]
where...
These Q's are probably simple for those of you who have/completed a course in Vector Calculus. But I'm only a higschool/secondaryschool student, so I haven't.
1. I'm not sure how the infinitisemal magnetic flux density d\textbf{B} from a wire element d\textbf{l} with a current I, which is...