Magnetism Definition and 974 Threads

Magnetism is a class of physical attributes that are mediated by magnetic fields. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. Magnetism is one aspect of the combined phenomenon of electromagnetism. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Demagnetizing a magnet is also possible. Only a few substances are ferromagnetic; the most common ones are iron, cobalt and nickel and their alloys. The rare-earth metals neodymium and samarium are less common examples. The prefix ferro- refers to iron, because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, Fe3O4.
All substances exhibit some type of magnetism. Magnetic materials are classified according to their bulk susceptibility. Ferromagnetism is responsible for most of the effects of magnetism encountered in everyday life, but there are actually several types of magnetism. Paramagnetic substances, such as aluminum and oxygen, are weakly attracted to an applied magnetic field; diamagnetic substances, such as copper and carbon, are weakly repelled; while antiferromagnetic materials, such as chromium and spin glasses, have a more complex relationship with a magnetic field. The force of a magnet on paramagnetic, diamagnetic, and antiferromagnetic materials is usually too weak to be felt and can be detected only by laboratory instruments, so in everyday life, these substances are often described as non-magnetic.
The magnetic state (or magnetic phase) of a material depends on temperature, pressure, and the applied magnetic field. A material may exhibit more than one form of magnetism as these variables change.
The strength of a magnetic field almost always decreases with distance, though the exact mathematical relationship between strength and distance varies. Different configurations of magnetic moments and electric currents can result in complicated magnetic fields.
Only magnetic dipoles have been observed, although some theories predict the existence of magnetic monopoles.

View More On Wikipedia.org
Recent contents Top users
  1. I

    Good study guide for Electricity and Magnetism?

    I wasn't really sure where to post this, but I am currently taking a second year Electricity and Magnetism course this term. I want to be able to do well in this course in order to keep my GPA up, but I don't have a particular interest in this class and the prof flies through the material at a...
  2. C

    Electricity and magnetism ( word problems )

    Homework Statement please cheack my answears and see if they are right, please help me solve the wrong ones thankyou ! (1)if you were to expend 10 J of work to push a 1 C charge against an electric field , what would be its change of Voltage ? voltage = electric potential energy /...
  3. bcrowell

    Classical Electricity and Magnetism by Edward Purcell

    Author: Edward Purcell Title: Electricity and Magnetism Amazon Link: https://www.amazon.com/dp/1107013607/?tag=pfamazon01-20 Prerequisities: Freshman mechanics. A year of calculus. Purcell introduces vector calculus from scratch, but most students who hadn't already had vector calc would...
  4. G

    Question about right hand rule (magnetism)

    Is the right hand rule for determining the direction of the magnetic field, force, and current only used when the aforementioned vectors are orthogonal to each other? Or, can the RHR be used in other cases as well?
  5. B

    Magnetism due to electron spin

    hi i have a doubt about magnetism i am assuming that magnetism is caused by spinning electric flux if we change the velocity(voltage) of the electron does the spin increase? how can we calculate spin of the electron which forces are responsible for electron spin
  6. N

    Is taking Electricity and Magnetism without Mechanical Physics a difficult task?

    Hey. So I switched from ChemE to Engineering-physics (I guess I followed my hearth here, instead of my head), and this entails I will have to take a course in Electricity and Magnetism this semester. During the previous one, the Engineering-physics guys took a course in mechanical physics, and...
  7. R

    Electricity & Magnetism + Quantum Mechanics?

    Electricity & Magnetism, Thermo + Quantum Mechanics? Hi! I've recently completed my first semester of college and it's offered me some insights. For example... the world is three-dimensional and, as such, multidimensional calculus exists! I managed to somehow survive Honors Mechanics but it...
  8. D

    Electricity and magnetism confusion

    Homework Statement I've been set an assignment and I'm struggling with one question in particular: Homework Equations 'Use the following data and plot the graphs for a point charge' 'Plot graph of E against r^2. Interpret the graph to describe electric field strength and electric...
  9. L

    Using magnetism to control the structure of concrete

    So this is my idea: make concrete using iron sand, preferably one with a decent ferromagnetic interaction. As the concrete sets, apply a magnetic field. The ferromagnetic particles align to the field creating a structure within the concrete. Possible to coat the iron sand in a retarding...
  10. R

    Earth magnetism and its application

    if magnetic field induce current then why satelites or spaceship doesn't gets electrified due to Earth magnetism
  11. DiracPool

    Magnetism in a current carrying wire

    If we use the right hand rule, we see that a hole current, or positive ion flow, creates a magnetic field around the wire where the flux moves in a clockwise direction. Counteractively, electron flow through a wire produces a magnetic flux that flows counterclockwise over the wire. Three...
  12. M

    Induction, magnetism and conductivity‏

    Relative motion between a permanent magnet and a conductor wire produces electric current in the wire. Would induced electric current be greater in a wire made of "magnetic" material like iron, "non-magnetic" material like copper, or it doesn't matter? In other words, is there relation between...
  13. denjay

    What makes Electricity and Magnetism a unified force?

    What makes Electricity and Magnetism a "unified" force? I'm taking upper level Electromagnetism and we've dealt with the various formulas dealing with electricity and magnetism. It seems to me that we are still largely dealing with them separately. In that, I mean we have a thing called a...
  14. O

    Motion in a magnetic field [Magnetism]

    Homework Statement This is not hw, but practice for my upcoming exam. Any help will be appreciated :) A charged particle of mass m = 6.7X10-8 kg, moving with constant velocity in the y-direction enters a region containing a constant magnetic field B = 1.6T aligned with the positive z-axis...
  15. J

    Questions about magnetism and spin.

    I just read a couple articles on angular momentum and spin... So what is the difference between the spin of a planet on its axis and the spin of an electron on its axis(because they both have angular momentum, right?) Also, if it is the spin of an electron that creates and determines magnetism...
  16. phosgene

    Why does the given diagram not violate Gauss's law of magnetism?

    Homework Statement I'm basically just wondering why the given diagram wouldn't violate Gauss's law of magnetism...there are two B-field lines exiting, but none entering the red box. So the net flux isn't zero. I vaguely remember the lecturer addressing this when we were studying the topic, but...
  17. Physicist50

    The Magnetism of Compasses: A Billion-Year Question

    I was wondering that if a compass was left on a horizontal angle for billions of years, would the north and South Pole needles eventually rip apart due to the north needle being repelled from the south needle, and vice versa, or could the magnetic field of either needle block the magnetic field...
  18. J

    How do I integrate Gaus's Law for magnetism for surface of half sphere?

    The problem shows a picture of a surface of a half sphere. It is labeled surface 1 being the disk of the top of the half sphere. Surface 2 is the remaining surface of the half sphere. R is the radius. The magnetic field is uniform and makes an angle theta with the vertical (or with the...
  19. B

    Comparing Current, Force, B Field, Magnetism

    Homework Statement Please see the attachment and see where i went wrong... simple T/F questions Homework Equations The Attempt at a Solution Here's what i tried 1. T (Right hand rule for both I1 and I2 where I2=-I1 2. F (Since I2 has no current, there is no B field from I2...
  20. P

    How Much Current Sustains the Suspended Copper Wire?

    Homework Statement A long horizontal wire carries a current of 48 A. A second wire, made of 3.0 mm diameter copper wire and parallel to the first, is kept in suspension magnetically 15 cm below. Determine the magnitude of the current in the lower wire. Homework Equations μI / 2∏r The...
  21. H

    What is the deal with kinetic and potential energy, electricity and magnetism

    Hello, Firstly i am new here ( not offering an excuse) and an on and off lurker to this awesome forum. I am trying my best to fit into the established rules ,sorry if i broke any inadvertently. If kinetic and potential energy represent the same things why are there entities representing the...
  22. R

    Magnetism & Photons: Research, Rare Phenomena & Invisibility

    Im looking to do a little research on the effects of magnetism on photons. Can someone point me in a good direction to start? Any rare phenomena that is worth mentioning concerning this subject? Also, I read a while ago that scientists can bend light around small objects and make them invisible...
  23. J

    How do photons interact in magnetism and how is the force felt

    I understand that as one person here puts it "The electromagnetic interaction is mediated by the constant exchange of photons from one charged object to another. Some electromagnetic interactions involve "real" photons or "virtual" photons instead." But suppose I have 2 magnets and push...
  24. B

    Textbook for junior level electricity and magnetism

    Since the instructor of my course doesn't use a textbook and just teaches based off his notes, what would be a good text to supplement my learning (when asked what he recomends, he just said find something in the library). Does electrodynamics = electricty and magnetism? I've heard this one is...
  25. J

    Electricity & Magnetism Honors Project Ideas?

    I am going into my fall semester of E&M and am trying to decide upon a topic to write about for an honors project. I have not taken an E&M course yet so it is difficult for me to really find which topics are too advanced scientifically or mathematically at this point. So far I have taken a...
  26. L

    Preparing for Electricity and Magnetism (advanced, undergraduate level)

    Hello PF, I am a few weeks from starting my second year as an undergraduate. This fall I will be taking the Electricity and Magnetism course for physics majors (crosslisted for graduate students). Last spring I took the introductory physics course on electrostatics and magnetostatics. The...
  27. D

    Magnetism & Electricity (2 magnets - Field)

    I am trying to calculate the output voltage for 1 coil in an axial generator/altenator I have 2 magnets with Br Max 13200 Gauss on opposing sides of the rotor (N-S facing), The coil is between them on stator. Using faradays equations what is the effective Br (Gauss/Tesla) that should be used...
  28. O

    Can Strontium's Paramagnetism Be Explained by Its Electron Configuration?

    From what I've learned atoms with unpaired electrons are paramagnetic and those without are diamagnetic. Strontium has electron configuration of [Kr] 5s^2 so why is it paramagnetic?
  29. S

    How Does Current in a Wire Create a Magnetic Field?

    hi , i wanted to ask why does current in a wire produces a magnetic field ? and can anyone explain how maxwell related electricity and magnetism , easily (im in high school)
  30. S

    How to determine material of metal (magnetism)

    Homework Statement Three bars of metal are known to be brass iron and steel. A magnet was used to distinguish between them. (the metal bars are placed under the south pole of a bar magnet and are used to pick up tacks) Metal 1 picked up 10, metal 2 picked up 6 and metal 3 picked up 2...
  31. S

    Electricity and magnetism (magnitude of magnetic field)

    A 1000-turn toroidal solenoid has a central radius of 4.2 cm and is carrying a current of 1.7 A. What is the magnitude of the magnetic field inside the solenoid at the central radius? (μ0=4∏×10^-7 T ∙ m/A) r= 4.2cm= 0.042m B=(μ0)(I)/(2∏)(r) ⇔ (4∏×10^-7)(1.7)/(2∏)(0.042) ⇔ 1.43x10^-8 T? Or...
  32. S

    Electricity and magnetism (magnitude of current flowing)

    If the area of a tube is 0.0000283 m, with moving ions contributing to a magnetic field of 44.0x10^-4 T. What is the current flowing through the tube? [permeability of free space 'mu subzero'= 4∏x10^-4]. I don't have a clue of how to start attacking this problem, have a genius professor, but...
  33. M

    How do relativity and magnetism affect each other?

    i apologise if the following statements may sound a little unscientific, or appear to beat about the bush. Now if two positive charges are traveling together side by side with a certain velocity wrt to me, i will witness a magnetic attraction between them. But if i am traveling together with...
  34. F

    Effect of magnetism on water molecules

    Does anybody have ideas for experiments that I can perform to investigate the title? I am working on a science project at the moment. Thanks very much for any help given.
  35. cryora

    Does Newton's Third Law apply to magnetism?

    Newton's Third Law states that every action has an equal and opposite reaction. I'm wondering if and how this applies to magnetism. I would assume that it would mean if a moving charge is creating a magnetic field that causes a magnetic force on another charge, then it can be said that the...
  36. R

    Magnetism of Hematite Cylinders: Laser Carving & Effects

    Scenario: You have a small, magnetized, cylinder-shaped hematite. The positive pole is on top and the negative pole is on the bottom. You took a laser to carve a new, smaller cylinder. After you're done carving, you are left with a smaller cylinder and a ring. Here are my questions: Will...
  37. P

    Which Book Best Explains Magnetism in Materials?

    I am looking for a good book that covers magnetic properties in materials. I've taken E&M (we used Purcell), and it only covered magnetism in materials briefly.
  38. M

    How does the electromagnetic force unify electric and magnetic forces?

    This may at first seem like a very stupid question, but I can't seem to get to the root of magnetism. As we all know, all charges exert electric forces on each other, and point charges obey the inverse-square law. I know how a moving charge generates a magnetic field according to...
  39. H

    Origin of Magnetism: Exchange Coupling Existence

    does the exchange coupling exists between atoms or between domains in magnetic substances?
  40. C

    Studying Self Studying AP Physics C: Electricity and Magnetism

    No, you didn't read the title wrong. I am really self studying a physics class. I just finished Mechanics (Physics I) and since I want to go to college to study physics to become an engineer or physicist. I need to take the next class, E&M (Physics II, Electricity and Magnetism). However, I...
  41. TheTank

    Thinking about electricity and magnetism, and some relativity

    I have 2 questions. I have been thinking about these two things a while, and got no one to ask, so hope to get some info/answeres here:) 1: When an electron is standing still, it produces an electric field (and no magnetic field), right? So when many electrons is moving with a constant...
  42. A

    Question about magnetism and electricity

    Does the force of magnetism cause electricity?
  43. H

    Basic magnetism on square loop question?

    A square loop carrying a current I creates its own magnetic field. Describe the forces on each side of the square loop due to its own field. What is the torque it experiences? My question is this. I know we can use bio savart. But for bio savart, B=uoI/2piR, what R do I use? suppose i have a...
  44. O

    Gauss's Law for Magnetism Question

    Hey everyone, I'm new to these forums. Being an electrical engineering major, most of my teachers aren't very concerned with the "physics" side of things. I'm hoping I can gain some insight on Maxwell's equations. When first stating Gauss's Law for Magnetism, the only reason my electromagnetics...
  45. G

    Need help understanding magnetism? Check out this comprehensive tutorial!

    Hi guys, I have been self-studying physics since sometime Its been going great,but I was reading yesterday on magnetism their some stuff that my book doesn't cover and assume you already know how to do it. For example If we place a compass between two mangetic field or three or more we need...
  46. C

    Magnetism as a relativistic effect

    So my physics teacher has been trying to explain magnetic forces in terms of electric forces and relativity but I'm still confused. If there is a wire carrying a current and I'm an electron traveling next to the wire at the same speed the electrons in the wire are traveling, the electrons in...
  47. H

    Is there a quantum theory of magnetism?

    After asking my teachers the same question, I came away with the impression that the classical field model was as far as magnetism went, as if after Maxwell's macroscopic laws there had been no development into a quantum theory of magnetism. Were they wrong? Additionally, if they were to some...
  48. C

    Question on magnets and induced magnetism

    Homework Statement I was just thinking, let's say I connect the north pole of 2 magnets to a ferromagnectic material on both ends, does the whole ferromagnetic material become a north pole? Drawing attached. Homework Equations Nil The Attempt at a Solution I think so.
  49. X

    Is Magnetism one of the hardest topics in Physics?

    I've been working out of Edward Purcell and I was doing fine till I reached the chapter on magnetism today. I found it to be quite difficult and had to stop my studying because I just wasn't getting it. Is Magnetism generally regarded as one of the harder topics in physics? Tomorrow I will try...
  50. U

    Magnetism seems absolute despite being relativistic effect of electrostatics

    I know that magnetic force due to a current carrying wire on a test charge moving w.r.t the wire(along the wire), can be interpreted as the electrostatic force if we use the first order relativistic corrections for Time Dilation or Length contraction of the charges of the wire, in the frame of...
Back
Top