What is Magnetic field intensity: Definition and 20 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,







{\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.

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  1. S

    I How do I visualize the magnetic field?

    Hi! So my question is this, I have done measurements with an magnetic field meter around a transformer from 0.5 meter away (then measure some points around) and then I moved out 0.5 meters and so on until I reached a nearby building. So my issue now is I want to visualize this to my customer...
  2. AndrewC

    Magnetic field intensity, flux density and magnetization of coax cable

    Inner conductor radius = 1cm outer conductor radius = 10cm region between conductors has conductivity = 0 & 𝜇r = 100 𝜇r = 1 for inner and outer conductor Io = 1A(-az) 𝑱(𝑟) = (10^4)(𝑒^-(r/a)^2)(az) Problem has cylindrical symmetry, use cylindrical coordinate system. Find the total current...
  3. Beelzedad

    Why am I getting Maxwell's second equation wrong?

    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...
  4. TheBigDig

    Find the time dependent magnetic field intensity

    Homework Statement Calculate the time-dependent magnetic field intensity B(t) at an axial distance r from a long, thin straight copper wire that carries a sinusoidal current with an alternating frequency of 50 Hz and a maximum amplitude of 0.5 A. Homework Equations I = Asin(\omega t) B =...
  5. K

    What is the EMF generated in a Straight Conductor?

    Homework Statement What is the EMF generated in a straight conductor of length L placed in a time varying magnetic field B as shown in the below figure.. Homework EquationsThe Attempt at a Solution Time varying magnetic field is B.cosωt, EMF = (d/dx)(B.L.cosωt) = -B.L.ω.cosωt I don't know...
  6. RobertColman

    How can I derive a formula for change in B field strength?

    I'm a bit stuck on this question (which is homework so hints are more welcome than outright answers). The question is: A very long wire carrying a current I is moving with speed v towards a small circular wire loop of radius r. The long wire is in the plane of the loop and is too long to be...
  7. Julian102

    Find magentic field intensity.

    Homework Statement A square with each side of 5 cm in length.Now if 4 parallel wires in each 4A current is flowing were placed on the vertex of the square.How can I find the center of the square of the magnetic strength? Homework Equations I am not sure what equation should be used.If I knew I...
  8. N

    Magnetic field intensity and density

    Hello folks, Can anyone explain to me what is the difference between magnetic field intensity H and magnetic field density B?
  9. R

    What is magnetic field intensity H?

    Hi all, My question is, in electromagnetism, magnetic field intensity H is equivalent to electric field intensity E , right?? Now, definition of E says that E is the force experienced by an unit positive charge in an electric field created by a source charge. So what is the definition for...
  10. D

    Calculate magnetic field intensity

    Homework Statement Two infinitely long filaments are placed parallel to the x-axis as shown in Figure 1. a)Find H at the origin b)Find H at (-1,2,2) Homework Equations ∫Hdl=Ienclosed H=H1+H2 The Attempt at a Solution Well following the equation above I get Hl= Ienc then...
  11. S

    Magnetic field intensity problem

    Hi everyone here, hope you enjoying this summer .. i'm taking ' elements of electromagnetic ' course this summer session and i just have a little question here in the yellow shaded statement shouldn't it be dl = (l/N) dz instead of dl=(N/l) dz ? By the way, it's not a HW...
  12. J

    Using Ampere's Law in finding H (magnetic field intensity)

    Homework Statement Let the regions 0 < z < 0.3 m and 0.7 < z < 1.0 m be conducting slabs carrying uniform current densities of 10 A/m^2 in opposite directions. Find H (the magnetic field intensity) and different z positions. Homework Equations Biot-Sarvot Law: H = ∫ (I dL X r)/ (4∏R2)...
  13. C

    How do i rank magnetic field intensity given amperes?

    Is the magnetic field intensity at point P stronger at 2 amps or 4 amps at point P (just outside each electromagnet), if they both have equal amounts of turns of wire. No relative equations. I know that magnetic field intensity is stronger as the number of loops are increased but I...
  14. M

    Electromagnet offset between applied voltage and magnetic field intensity

    I'm trying to find a mathematical formula between applied tension and resulted magnetic field intensity on an electromagnet. I know that between the voltage and the electric current there is a pi/2 offset, but in practice there is a bit more than actually pi/2 offset probably something that...
  15. O

    Investigating magnetic field intensity of eddy currents

    How would I calculate the magnetic flux density of the magnetic field generated by eddy currents induced in a circular plate? I decided it would be reasonable to approximate this by considering the flux density of a current loop. However, it is my understanding that eddy currents are induced...
  16. M

    Measuring Magnetic Field Intensity (H) and Magnetic Flux Density (B).

    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...
  17. E

    Getting E-Field from magnetic field intensity, H

    Homework Statement Given the magnetic field intensity, H, find E. H=\hat{y}6cos(2z)sin((2x10^7)t - 0.1x) Homework Equations \nabla \times E = \frac{- \partial B}{\partial t} The Attempt at a Solution Since we have H, we can use the relationship that \muH = B and then take the...
  18. S

    Magnetic Field Intensity and Point Charges

    Homework Statement Positive point charges q_1= 6.90 microC and q_2= 2.90 microC are moving relative to an observer at point P as shown in the figure. The distance from the observer to either charge is originally d = 0.190 m.The two charges are at the locations shown in the figure. Charge...
  19. S

    Magnetic field intensity questions

    I tried reading my textbookfor the answers to these questions, but I can't find an answer. Can someone answer these questions? 1. Changing the magnetic field intensity in a closed loop of wires induces A. Current B Voltage C. Both D. Neither 2. True or False: Energy emitted by...
  20. S

    Magnetic Field Intensity Question

    This is for an assignment that is due next Monday for me. I'm kind of confused here for how to calculate the magnetic field intensity at all points for the conductor(s) in the diagram I have attached. First, there is a cylindrical conductor of radius a, then surrounding it is another conductor...