What is Magnets: Definition and 562 Discussions

A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, cobalt, etc. and attracts or repels other magnets.
A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include the elements iron, nickel and cobalt and their alloys, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Ferromagnetic materials can be divided into magnetically "soft" materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically "hard" materials, which do. Permanent magnets are made from "hard" ferromagnetic materials such as alnico and ferrite that are subjected to special processing in a strong magnetic field during manufacture to align their internal microcrystalline structure, making them very hard to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied, and this threshold depends on coercivity of the respective material. "Hard" materials have high coercivity, whereas "soft" materials have low coercivity. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization.
An electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Often, the coil is wrapped around a core of "soft" ferromagnetic material such as mild steel, which greatly enhances the magnetic field produced by the coil.

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  1. 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.
  2. X

    Why don't magnets violate conservation of energy?

    One thing that always puzzled me was that to me, magnets seem to violate the law of conservation of energy. They obviously do not, and it is purely my ignorance that is allowing me to think this, but I need some explanation as to why they don't. What I mean by this is the following.. Say...
  3. B

    Use of magnets to create power?

    Hi i have just joined and this is my first post.I was hoping to find out if anyone has(using only fixed magnets) created a propulsion or any kind of power generator.I have a few ideas that id like to try, although there probably fundamentally flawed, if no one else has achieved it. All and...
  4. A

    Calculating the force between Magnets

    How do I find the force between the poles of 2 identical permanent magnets separated by a distance? (experimentally not theoretically)
  5. A

    Forces of Magnets Attraction>Repulsion?

    Hello I have come across a video that interested me, (Attraction vs Repulsion in Magnetic Fields 2) http://www.youtube.com/watch?v=8sUpFc-0yg0&feature=related In this demonstration it shows the attractive magnetism is stronger than repulsive. 1) From this is it safe to say that the force...
  6. M

    Can a stationary bar magnet attract free electrons to generate electricity?

    I know that magnetic fields can effect electrons in certain ways, but I specifically want to know if a bar magnet just sitting on a desk will attract "free electrons" much like a magnet will attract a paperclip. The reason for this question is my brother is working on a new type of battery that...
  7. T

    Magnets strength/repel, total movement?

    Hey guys. Not a homework question. If two magnets have the same friction, same mass, etc. But have different strengths. and they are arranged so that they will repel each other, how will they move in relation to their starting points? Will they both move 1/2 the distance of the...
  8. F

    Hypothetical Question of Virtual Particles and Magnets

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  9. W

    Perpetual machine by using free energy of magnets Possible?

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  10. N

    Six cylindrical magnets arranged N-S-N-S-N-S formed into a ring hold shape?

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  11. N

    Fluid mechanics observation relative to neodymium magnets question.

    Watch this video first, please. ( http://www.youtube.com/watch?v=2ghBUcQG1lQ&feature=related ). I had been imagining magnetism in general as fluid motion and not like it is portrayed now days for the last few years. Disregarding the hundreds of notes and all that, what I did notice was this...
  12. L

    Calculating the force exerted on structure by two large permanent magnets

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  13. J

    Forces on multiple cylindrical magnets stacked

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  14. N

    Conservation of energy and magnets

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  15. E

    Energy Loss From Permanent Magnets

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  16. A

    (Magnets) Is the attractive force stronger than the repulsive force?

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  17. C

    Attraction of magnets to ferromagnetic materials with distance?

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  18. H

    Why magnets attract or repel each other

    I would like to understand at a microscopic level why magnets attract or repel each other. I understand that there are tiny loops of currents caused by the spin and orbital rotations of electrons, that there are magnetic moments, but I don't understand why magnets attract. How is the magnetic...
  19. M

    Magnets attract and oppose, right?

    then why has no one built an engine that requires no wires, no copper. no batteries, capacitors, resistors, no electricity whatsoever? if a magnet is strong enough it can push or pull something, right? then why aren't wheels magnetic? generators, engines, rotors, hard drives...why is...
  20. Vorde

    Exploring Magnetism: Understanding the Attraction of Non-Magnetic Metals

    I haven't had any formal teaching on magnetism, so my guess is this is an obvious question with an obvious answer, but I can't produce it myself. Are non-magnetic metals attracted equally to both north and south magnetic poles?
  21. S

    Exploring Hall Effect with Semiconductors and Magnets

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  22. N

    Propelling A Small Rocket With Magnets?

    My senior project for high school is to prove that NASA can make their launch more efficient by adding electromagnets to launch. I was thinking just magnets lining a tunnel coming from underground that move the payload a lot like a maglev. My job is to make a model of this, and I'd like to make...
  23. J

    How can magnets repel paperclips?

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  24. B

    Exploring the Mysterious Attraction Between Permanent & Superconducting Magnets

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  25. J

    The physics of rattler magnets

    The physics of "rattler" magnets I have been playing around with these magnets (mine are 5.5cm long, 1.5cm diameter at the central bulge), and some of the effects I am not quite sure how they work, although I have some ideas. These are the effects: First, their actual function, the "rattle"...
  26. D

    Electrical conductivity of magnets

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  27. M

    Do neodymium magnets loose energy?

    Generally, most of the research I have done says that neodymium magnets do not loose their energy, even when dropped or around other magnets, and will last 400 years. But what about if the neodymium magnets are constantly in motion and interacting with each other? Our system has a Sphere...
  28. B

    Magnetic Fields interaction with other magnets

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  29. J

    Polarity of magnets, Simple?- confused me.

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  30. M

    Magnetic Forces in Vacuum: FAQs

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  31. S

    Ferromagnetism, what's happening in cylindrical magnets?

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  32. J

    Using magnets to suspend objects

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  33. B

    Magnetizing Magnets Through Steel: Answers to Your Questions

    Hi, I once read (but simply now cannot find the site again!), that if you magnetize a magnet through steel, you can make it thousands of times stronger. Is this when you create the magnet, or does this mean when you build a magnetic generator, you need to attach the magnets to steel to...
  34. P

    What happens to magnets held in certain position indefinitely?

    Hello, Can someone here settle a debate for me? A friend of mine said that if you hold two neodymium magnets 1" or so apart from each other with attracting ends (N-S) facing each other for prolonged periods of time (years and years), nothing will happen to the magnetic field. I stated...
  35. S

    Do fields created by magnets add up?

    If I were to use a gaussmeter to measure the strength of a magnet's magnetic field, would the value read be double if I were to stack two (of the same kind of magnets) on top of one another?
  36. C

    Ring magnets levitation question

    consider the image i have uploaded, it shows 4 ring-shaped magnets of different sizes each pair of concentric magnets are held in position relative to each other, and the lower pair is also affixed to the ground, i.e. the upper pair of magnets is free to move blue and red faces show the...
  37. C

    Do Large Generators Really Use Permanent Magnets?

    I frequently teach my students about how basic generators work (motional EMFs, Faraday's Law, magnetic flux, etc.). Question: do the generators used at large power plants really use a permanent magnet as a source of the magnetic field? I was thinking that maybe an electromagnet might be...
  38. T

    Questions about magnetic force between different strength magnets

    Hi, I have some very basic question that I've been struggling to find the answer to and before I go and buy some magnets to do some test of my own I thought I'd ask here: Do two magnets of different strength repulse each other at the same strength, or does one repulse the other more...
  39. C

    Making Bar Magnets: Heating & B Field Placement

    If I wanted to make bar magnets would I heat up the metal and then place it in a B field of a solenoid and then cool it down in the field to keep the magnetization? It seems if i heated it up first the atoms would be more easily aligned in the B field, And then cool it down to preserve this state.
  40. S

    Do magnets have a longer reach in a vacuum chamber?

    Do magnets have a longer reach of attraction in a vacuum chamber?
  41. davenn

    Induced voltage with coil between 2 magnets

    hi gang, Just building a seismometer I have 2 x 2.5cm disc rare Earth magnets spaced far enough apart for a coil of wire to move between them. Would you expect there to be any difference in induced voltage into a coil between 2 magnets when the magnets are orientated to attract or repel ...
  42. M

    Using magnets to transfer power through metal?

    Hey guys. A friend and I are planning on making a scuba diver tow device for his trip to the florida keys. We could just put a trolling motor exposed to the water, but at depth I have reason to believe water would push past the seal. So what we are hoping to do is weld up a thin wall steel...
  43. D

    Potential Energy between two magnets, and potential energy of gas

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  44. K

    Can permanent magnets be modeled as set of magnetic charges ?

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  45. E

    Using Magnets to Create Perpetual Motion?

    Let's say I have permanent magnets set up in a sort of half sphere with the inside of the sphere pointing up and it laying flat on a table and then I have a ball with, let's say, half the radius of the half sphere. The ball has the same permanent charge as the half sphere. I place the ball over...
  46. K

    Do electrons flow in one direction in magnets?

    Do electrons continuously flow from north to south pole in magnets. If yes, does this continue to happen when the magnet is attracted or repelled by another magnet or to a ferrite?
  47. M

    Thermodynamics - Rods, bubbles and magnets

    Homework Statement For an elastic rod, show that \[ \frac{\partial C_{L}}{\partial L}_{T} = -T*\frac{\partial^2 f}{\partial T^2} where C_{L} is the heat capacity at constant length L. Homework Equations dU = Tds + fdL F = U - TSThe Attempt at a Solution I've used dF = dU - Tds - SdT = fdL -...
  48. S

    Discover the Force of Levitation with Magnets: Levitron Physics Explained

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  49. A

    Double-slit experiment with magnets and iron projectiles

    Hi, I am not sure if this kind of experiment has been performed before. If so, great, I would love to see the results. Anyway, here goes. The double-slit experiments with photons, electrons and even...
  50. F

    So, why do magnets feel easier to attract than to pull away?

    Homework Statement I know this is going to sound like voodoo or something. But why do magnets feel easier to attract than to pull away? Let me elaborate. Suppose a south pole and a north pole is near each other, they attract. Suppose a north pole and a north pole together, they repel...
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