Magnetic Definition and 1000 Threads

  1. L

    Usage of absorption and magnitude mode spectra in nuclear magnetic resonance

    In nuclear magnetic resonance, when should one process spectra in absorption mode and when - in magnitude mode? What is benefit of using the first one and the second one? For example, I need to integrate spectrum. In this case, what should I use - absorption or magnitude mode?
  2. fight_club_alum

    Exploring Magnetic Forces on Current: A Visual Guide

    This is how I visualize the problem (of course I am drawing this as if it is in the z-y axis); I don't know what will be the next step. Anyone please help me. Thank you
  3. K

    Cell Metabolism and Static, Unidirectional Magnetic Fields

    Can anyone explain why an artificial magnetic field may or may not promote an increase in cellular metabolism?
  4. B

    Do magnetic lenses do work on particles flowing through them?

    Do magnetic lenses do work on charged particles flowing through them? Intuitively I would think yes because the magnetic field produced by the electric current in the coil is applying a force on the particles flowing through the lens, so therefore an electric current (the beam of particles to...
  5. K

    Magnetic field around a conductor with protons?

    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.
  6. fight_club_alum

    Particle in a circular path due to magnetic field

    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
  7. T

    Expressing the magnetic vector potential in terms of its curl

    We have the retarded magnetic vector potential ##\mathbf{A}(\mathbf{r},t) = \dfrac{\mu_0}{4\pi} \int \dfrac{\mathbf{J}(\mathbf{r}',t_r)}{|\mathbf{r}-\mathbf{r}'|} \mathrm{d}^3 \mathbf{r}'## And its curl ##\mathbf{B}(\mathbf{r}, t) = \frac{\mu_0}{4 \pi} \int \left[\frac{\mathbf{J}(\mathbf{r}'...
  8. fight_club_alum

    Path diameter difference of two singly-charged ions in a magnetic field

    M1(50,000)/q (0.4) - M2(50,000)/q (0.4) = 0.025 Is there a special charge for singly charged ions?
  9. fight_club_alum

    Particle that moves in an electric and magnetic field

    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
  10. N

    Magnetic attraction and repulsion equivalence

    Equations of attraction or repulsion can get very complicated when the field shapes and densities are not identical. Intuition would hold the forces to be the same, but in on closer examination the field shape of two repulsing magnets looks entirely different from two attracting magnets. I...
  11. K

    Find ∆V while sliding a card through a card reader with magnetic field

    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.
  12. K

    Strength of magnetic field at the end of a wire wrapped nail.

    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...
  13. fight_club_alum

    Calculating Magnetic Force with Vectors

    8000 0 0 5 -4 3 F = (5 x 10^-6) * up (sorry can't write a materix here) F = (5 x10^-6) {0i - 24000 j - 32000 k) F = -0.12 j - 0.16 k Mag of F = 0.2 (I feel that there is something wrong in the question; I don't know)
  14. fight_club_alum

    Find the charge of this particle moving in a magnetic field

    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
  15. dRic2

    Magnetic Monopole: Reason Behind Faraday's Law Counterpart

    For the magnetic fields it is obvious that ##F = q_m B##, but I don't get why the final result is $$\mathbf F = q_m(\mathbf B -\frac 1 {c^2} \mathbf v \times \mathbf E)$$ The second part is like a "counterpart" of Faraday's Law, but I do not understand why it should be there... For what reason...
  16. H

    Work performed by a magnetic field

    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...
  17. Wayne Lai

    Acceleration of a metal piece due to dipole radiation magnetic field

    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...
  18. N

    Magnetic force on a wire due to a loop

    I just need to confirm my intuition that the magnetic force on the wire carrying I2 is 0. Basis for my intuition: * Right above the center of the loop carrying I1, the magnetic field lines are in exactly the same direction as the piece of wire carrying I2, so [a] x [B1] = 0. (photo from...
  19. Y

    Magnetic force -- does it fall off to zero far away from the source?

    Let's say we have a wire and a circuit is closed the magnetic field start to spread with speed of light c. Then we would have a place " out of range " at which the magnetic field doesn't exist.What is the equation that connects magnetic force with distance with its prorogation of speed of light...
  20. themountain

    The magnitude and direction of the minimum magnetic field

    F=ILB F=(48)(.76)B F/36.48=B I am stuck at how to find F, is there a different formula I am missing?
  21. Sureshbaliyan

    Linear acceleration by using Magnetic strips

    I am working with Magnetic strips to get countinous force in both clockwise and anticlock wise direction. I am looking for better concept for hand free mode in my experiment. The pdf file of my experiment is attached .
  22. TheBigDig

    Force on a magnet in a magnetic field

    So I'm kinda stumped. I'm assuming that since ##\vec{m}||\vec{B}##, the x and y components of both are zero. But I'm unsure how to take this further.
  23. S

    Magnetic field of plane with thickness d with uniform surface current

    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...
  24. Wesleyk89

    Extend Magnetic Field Density from magnetic object's surface?

    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...
  25. J

    1 mm magnetic shield of pure iron same as 1 cm of mu-metal?

    When materials with high permeability are used to shield against low EMF frequencies of the order of 10 Hz, is the effectiveness linearly dependent on thickness and permeability? In other words, pure iron (mu=200,000) can be 10 times thinner than mu-metal (mu=20,000) for the same result with a...
  26. NavStar

    Static free charge in a time varying infinite uniform magnetic field

    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...
  27. B

    How would you find the magnetic force on a piece of metal by an electromagnet?

    Does the metal being attracted make a difference? How would you find the force on the metal knowing the field strength there? How would you even calculate the field strength of an electromagnet with a core? In my case, it is one of those junkyard electromagnets. thanks
  28. gibberingmouther

    Magnetic Fields from Current Carrying Wires

    I've had a lot of problems that involve a segment of current carrying wire, for example when you have a square loop of wire. I have a formula for "long" wires that is B = μ0 * I/(2 * π * d). Can I use this for shorter wire segments, and if not, what formula can I use?
  29. A

    Trajectory of charged particles in a magnetic field?

    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?
  30. JD_PM

    Arguing about the magnetic force vector

    I am writing about the nature of force in classical mechanics and what does really imply, in terms of change in motion. I am using as an example a circuit, on which we exert a force. I am trying to justify the following scheme (concretely, ##f_{mag}##): The thing is that I am wondering how...
  31. M

    Magnetic field "lines" confused with magnetic field "vectors"

    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...
  32. Y

    Determining The Magnetic Saturation of A Soft Iron Magnetic Core

    Hello friends. I know there a lot of complex mathematic involved in this subject and I'm not currently very knowledgeable in that area but, in simple terms, what would be the simplest way (theoretical or practical) to determine the magnetic saturation of a cylindrical soft iron magnetic core...
  33. Behrouz

    Creating a Magnetic Snow Globe: Lightweight Options

    I'm trying to make a magnetic globe (magnetic from outside) with diameter of about 30 cm. Please imagine it as a snow globe, while it is magnetic as well :). I'm wondering about the options to make it, as light as possible. Please feel free to suggest tags here, if I'm missing anything or I...
  34. J

    Loop falling in a magnetic field

    (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...
  35. A

    Acceleration of an electron due to Magnetic and Electric fields

    I figured that we would simply add up the forces acting on the electron (the electric force Fe and the magnetic force Fb) and then equate this to the given acceleration multiplied by the mass of the electron like so. vector Fe + vector Fb = (mass of electron) (vector acceleration) since vector...
  36. Zack K

    Forces acting on a coil due to a varying magnetic field

    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...
  37. K

    Square wire in a cylindrical magnetic field

    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. $$\hat{\phi}=-sin(\phi)\hat{x}+cos(\phi)\hat{y} \therefore \hat{\phi} =-sin(tan^{-1}(x/y))\hat{x}+cos(tan^{-1}(x/y))\hat{y}$$...
  38. sombr1o

    Magnetic field from a thin current-carrying cylinder

    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.
  39. TheBigDig

    Magnetic field of vector potential

    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}}...
  40. archaic

    Magnetic flux (and flux in general)

    The general interpretation of flux as I understand it (and please correct me if I'm wrong) is that it represents how much something is going through another (surface or volume (and perhaps lines?)), I'll quote Khanacademy : Considering that magnetism is a force, I very well understand that we...
  41. H

    B Magnetic field and moving charge special relativity

    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...
  42. L

    Does the angle of the magnetic field affect sunlight?

    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...
  43. J

    Calculating the frequency of an electron orbiting in a magnetic field

    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...
  44. B

    Biot Savart Law with Different Magnetic Permeabilities

    I would like to make a program that produces a 2D heat map showing the magnitude of the magnetic field produced by a finite length solenoid. The heat map would show the field strength along the radial and axial directions of the solenoid. I plan to divide the conductor into "infinitessimally"...
  45. C

    Magnetic saturation and ferrite magnets

    Hi, I believe I understand the basics that permeability of materials is the function of change of flux density with magnetic field. So a non-magnetised material might have a high permeability (easy to increase the magnetic field) while a magnetised mass of the same material might well be close...
  46. Zack K

    Current induced on a coil by a changing magnetic flux in another coil

    I will first calculate the magnetic flux of the coil in motion. $$\frac {d\phi}{dt} = -\frac {dB_{loop}}{dt}A = -\frac{d}{dt}(\frac{\mu_o}{4\pi}\frac {2\pi NR^2I}{(R^2+z^2)^{\frac{3}{2}}})A$$differentiating in terms of ##z##, we get $$\frac {d\phi}{dt} =(\frac{\mu_o}{4\pi}\frac {6\pi^2...
  47. C

    Imperial-Metric Unit conversion for Magnetic Field Gradiometer?

    Hi all, I have a question which I think should be a simple solve for most people but I cannot seem to get my head around it. It is a common case in geophysical surveying that a magnetic field vertical gradiometer might be used. This instrument uses two magnetometers separated by a known...
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