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.

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  1. C

    Magnetic Field Due to a Curved Wire Segment

    For this problem, The solution is, However, why did they not use limits of integration for the integral in red? When I solved this, I used as limits of integration. I see that is not necessary since you get the same answer either way, but is there a deeper reason? Many thanks!
  2. C

    Magnetic Field Surrounding a Straight Conductor

    For this problem, Part of the solution is, However, would someone please tell me where they got the sine function circled in red from? Many thanks!
  3. J

    Calculating Area & Direction of Magnetic Field

    Hi, the problem statement is above. I have some questions about how to calculate the area and the direction of the magnetic field of this problem. As the magnetic flux, my professor have defined it as Phi= integral(B dS)=(Area)e_x B= (Area_triangle + (L^2/2) *(β + α(t)))*B e_z. How can one know...
  4. sal1854

    I Direction of motion of particles with total spin under magnetic field

    According to Chapter 8 of Griffiths' book Introduction to Electrodynamics, the magnetization force that acts on a magnetic dipole is $$F_M=\nabla (m \cdot B)$$, where ##m## is the magnetic moment and ##B## is the magnetic field. For a paramagnetic or diamagnetic particle...
  5. T

    I Origin of the Earth's magnetic field

    How can the motion of liquid iron consisting of neutral iron atoms in the earth's core create magnetic fields? What am I missing?
  6. Ahmad Sadek

    B Can a rocket flame be controlled by a magnetic field?

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  7. G

    I Magnetic Field vs Spacetime: Effects on Inertia Disk

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  8. S

    I How do I visualize the magnetic field?

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  9. V

    Why does a diamagnetic rod align perpendicular to a magnetic field?

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  10. S

    I Brownian motion of charged particles?

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  11. gentzen

    I Are there asymptotic QTF/QED states in a constant magnetic field?

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  12. guyvsdcsniper

    Determining Electric and Magnetic field given certain conditions

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  13. S

    I Can trains use permanent magnets to be propelled?

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  14. B

    EMF Induced by Changing Magnetic Field

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  15. C

    I Do objects of differing mass fall at the same rate in a magnetic field?

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  16. thedubdude

    I Why does metal moving though a magnetic field slow down?

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  17. besebenomo

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  18. warrenchu000

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  19. besebenomo

    Moving bar enclosing a changing magnetic field generates a current

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  20. besebenomo

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  21. P

    Induced EMF due to motion of a wire perpendicular to a magnetic field

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  22. X

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  23. B

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  24. arjun_ar

    Calculate the magnetic field from the vector potential

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  25. LCSphysicist

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  26. G

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  27. S

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  28. Adgorn

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  29. P

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  30. J

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  31. J

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  32. A

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    ##B_0 = \frac{\mu_0(N)(I)}{2\pi r}## ##\frac{N}{2\pi r} = 200## ##B_{net} = B_0 + B_m = (1+X)\times B_0## Plugging in the numbers: ##B_0 = 4\pi\times 10^{-7}(200)(1.5) = 3.8\times 10^{-4}## ##B_{net} = (1+X)\times B_0 = (1+ 3\times 10^3)\times 3.8\times 10^{-4}## = 1.13 T But the answers says...
  33. J

    EMF generated in a blood cell by an oscillating magnetic field

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  34. A

    I Does electron beam in empty space generate magnetic fields?

    Does electron beam in empty space generate magnetic fields around them just as with current in conductor. If yes, then is it experimentally proven that two parallel electron beam would attract each other.
  35. A

    Magnetic field generated by an infinitely long current-carrying wire

    Can someone explain how there can be a radial magnetic field? I thought the magnetic field was always tangent to the circle using the right hand rule where you wrap your fingers around the current and point your thumb in the direction of the current.
  36. J

    Find magnetic field at center of rotating sphere

    if a sphere rotates, it's like multiple currents going around in a circle. I can find the magnetic field of each of those currents at the center point of the circle and add them together. We can integrate with respect to y and R. y ranges from 0 to 5 cm away from the center of the loop and the...
  37. A

    Understanding Torque in a Magnetic Field with Loop

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  38. Sunny Singh

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  39. EmmanKR

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  40. L

    Flux of constant magnetic field through lateral surface of cylinder

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  41. Gbl911

    I Average Magnetic Field Between 2 Conducting Rods

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  42. Mr_Allod

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  43. I

    Directing magnetic field lines by using diamagnetic material

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  44. T

    A A question about charged particle in a magnetic field

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  45. Mr_Allod

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  46. Isopod

    B Could anything heat back up the core of Mars?

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  47. SanaiBongchul

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  48. Salmone

    I How to obtain Hamiltonian in a magnetic field from EM field?

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  49. S

    Potential difference of a ring rolling in magnetic field

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  50. E

    B Virtual photons as force carriers

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