What is Magnet: Definition and 907 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. T

    Can a magnet be made by friction?

    at work, i was using a tool which is used to tight objects to each other, and after a while, i put it on the table, and small steel pins sticked to it. the steel tool, i guess that every time i tight the tool to the metalic objects there was friction, and somehow it became a magnet. and...
  2. B

    Magnet Properties: Stick to Steel at 150°C?

    Hi friends, i have question will the magnet be able to stick to the steel ,when steel is at 150 degreee centigrade in same wave as it will stick to it at normail temperature. Please advice or give me the resourses to find magnet properties. Thanks Prashant Bidikar
  3. A

    Will a Magnet Damage My Credit Card?

    will i damage my credit card if i put it on top of a strong magnet? i have a few smart cards together with my credit cards in my wallet. when i use my smart card (like a security access card to open doors, gates with electronic access) i tap my wallet on the reading pad which i believe is...
  4. K

    Who does the work in lifting magnetic material with natural magnets?

    Lorentz force law tells us that workdone by magnetic force=0.Griffiths illustrates an example where work is done by the battery in a circuit.But I am intersted in something more.Who does the work of lifting some magnetic material when we use natural magnets?What is the way of energy...
  5. K

    Supercooled magnet- effects on other materials?

    If I were to take a permanent magnet and hold a piece of, say iron, a fixed distance away there would be constant attractive force generated between the two bodies. If I were then to cool the magnet down towards absolute zero, but keep the temperature of the iron constant, what changes would I...
  6. E

    Medical Understanding the Brain and MRI: How a Huge Magnet Affects Electric Impulses

    I only have a vague idea of how the brain and MRI work but from my understanding the brain uses electric impusles and an MRI uses a huge magnet. Since a magnetic force redirects a moving charge, why doesn't someone go crazy when they are in an MRI because the neurons don't go where they are...
  7. S

    Model for a flux pinning magnet

    model for a flux pinning What is the best model we can make for a flux pinned magnet? From readings on superconductor levitation research (https://www.amazon.com/gp/product/0471559253/?tag=pfamazon01-20), I found that the magnet feels a spring-like force and that the spring constant (K)...
  8. R

    Why Do Refrigerator Magnets Stay in Place Despite Gravity?

    I recently particpated in a thread that was closed out before I got the answer to what seemed to me a kind of paradox A permanent magnet attaches to the side of a refrigerator. IT won't stay there forever , but it will for a very long time. All that time gravity wants to pull the magnet...
  9. R

    How to Maximize the Strength of an Electric Magnet

    I am interested in building electric magnets. I have tried without success to find equations on what will make a stronger magnet. If I double the number of wraps, will the magnet be twice as stong? If I double the volts, will this make the magnet twice as strong? Does the type/gauge of wire...
  10. N

    Why magnet attract only metal ?

    I want to know that why magnet attract only metal but not all thing . Since all thing are made up of atom, what make the metal so difference so that it can be attract by a magnet ?
  11. S

    Center Pole Magnet: Can It Exist?

    I want you to help me settle an arguement. Is it possible to have a center-pole magnet? That is, a magnet with one pole at the center, and the other pole facing out in every direction? I think that it isn't, because the molecules would force each other to all face the same direcion, or all of...
  12. D

    When a bar magnet (one with Npole n the other with S pole) is broken

    When a bar magnet (one with Npole n the other with S pole) is broken into 2 pieces, wat poles do the pieces have? thanx
  13. M

    Removing magnetism from a magnet with electricity?

    Hey everyone, wondering if anyone knows if it's possible to remove the magnetism from a magnet through use of electicity. Specifically using 12volts, 2.5 amps DC. I'm looking for some kind of switch, or converter etc, that would remove the magnetism, but obviously I don't know exactly what...
  14. S

    Shake a magnet fast enough, would i create light?

    if i were to shake a magnet fast enough, would i create light?, and if so which direction would i need to shake it? away then towards, up and down or sideways?
  15. W

    Designing a three phase permenent magnet generator

    I am designing a three phase permenent magnet generator , and have a question. as a magnet pair passes over a coil , inducing a voltage, that voltage is most dependent on ? 1) the angular velocity ( that's a given) 2) the pole strength 3) flux density 4) energy product. 5) thickness of...
  16. I

    Can an Electromagnet Render a Bar Magnet Useless?

    hi I was just thinking at school we learned that a current running through a coil of wires with a iron core produces an electromagnet. so if you place a bar magnet instead of an iron core would this strenghten the magnet or if placed in opposite direction render the magnet useless (given that...
  17. Astronuc

    What is maximum magnetic field strength of SC magnet

    Another poster is looking for a 20T magnetic field or better, so I went looking for what has been reported as the maximum field strength for an SC magnetic field to date. However I found some contradicting claims. Is there a refereeing organization or a reputable source from which to...
  18. B

    Polarized Free Electrons vs Polarity of Static Magnet

    Question 1: Which type of free polarized electron (spin up or down) is attracted to the true North pole of a static magnet? Question 2: Why is a free electron attracted to or repelled by either pole of a static magnet?
  19. J

    Motion of Magnet on Inclined Plane: Info & Force Calculation

    Do you have any information about motion of magnet as it rolls down an inclined plane? Maybe some links. Or how to count the magnetic force which stop magnet? Thanks in advance
  20. T

    Magnet Valves: What Are They and How Do They Work?

    I'm doing some drawings on a cooling system, which includes a couple of so called "magnet valves". What excactly is a magnet valve, and does it actually have anything to do with the normal type of magnets?
  21. Q_Goest

    Large Project in Europe having a Superconducting Magnet

    I had a customer looking for some equipment that would be used in Europe to cool down a superconducting magnet that was to be installed there possibly in 2006. It must be an exceptionally massive magnet because he's looking for a very large cryogenic compressor and he says it will take 6 months...
  22. R

    Making a rather unusual magnet

    Hi, I am making myself a humbucking pickup for my guitar and I need a bar magnet with poles running from one long side to the other (refer to http://www.rehandalal.com/magnet.gif" )... It needs to be a relatively strong magnet. So if anyone could offer any suggestions as to what material I...
  23. S

    Changing taste of wine with a magnet?

    Saw this gadget on tv that's supposed to change the taste of wine with a special magnetic field. And the new structure of the wine is to last for 15 days. Would this be possible at all?
  24. L

    Levitating magnet and rotating superconductor,

    Look at this figure. http://img223.imageshack.us/img223/2136/rotatingsuperconductorandmagne.th.png What will happen to the repulsive force between magnet and superconductor?Would the repulsive force increase with rotation?
  25. A

    Donkey for a cart and the carrot for a magnet

    Me and my buddy had a discussion the other day. Imagine the scenario with the donkey that has a danglin carrot in front of him. If we swap the donkey for a cart and the carrot for a magnet, what would happen? My buddy was pretty sure that the cart would move, and I thought that it wouldn't...
  26. H

    Calculating Magnetic field of permanent magnet

    Hi: I'm having real trouble finding resources for the problem of accurately calculating (and drawing the field lines for) a magnetic field around a permanent bar magnet, or between two permanent magnets (I assume this is the same problem, as fields are superposable). I've found lots of sites...
  27. T

    What metals make the best cores for an Electro Magnet?

    I can't find any sort of charts for the stregths of different metals that i could use as the core for my Electro Magnet(EM). some plans for a E.M. would be kinda cool to see too if anybody has any. (also, this is my first post on this site and i am really excited because I've been lookin...
  28. Pengwuino

    Powerful Magnets: Benefits & Risks

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  29. S

    Magnet is (kind-of) incredible

    Electrons inside of a solid matter spinning around their respective nuclei, with their axes quite parallel with the axis of that object, and that's how a magnet constantly supplies magnetic field (nice!). NOW: If I say that the magnetic field from a natural magnet is a mean of constant flux...
  30. B

    Does magnet wire always have to be used in the production of solenoids

    Does magnet wirealways have to be used in the production of solenoids or Transmformers?
  31. M

    Average Domain Size & Permanent Magnet Creation

    what is the average size of a domain? and how are "permanent" magnets made? thanks, erin.
  32. L

    Why does the earth behave like a giant magnet?

    i have posted these questions in the chemistry forum but I have not receive any replys. Perhaps I have posted the questions in a wrong forum. why does the Earth behave like a giant magnet? why the hole in the ozone layer is above Antarctica but not polluted continents? in a fractional...
  33. L

    Why does the earth behave like a giant magnet?

    why does the Earth behave like a giant magnet? why the hole in the ozone layer is above Antarctica but not polluted continents? in a fractional distillating column of liquid air, the 'exit' of oxygen gas (b.p. -183C) is below the argon gas (b.p. -186C). However, when the liquid air...
  34. J

    Calculating Moment of Inertia of a magnet

    Hello all, I have a ceramic doughnut magnet (from a speaker) and I'm wondering how to calculate its moment of inertia. I'm using a simulation program to do some mechanical analysis and I need to spin the doughnut magnet. It weighs roughly 185 grams, the inner diameter is 1.25in, the outer...
  35. P

    Xtracting energy out of a magnet

    In a dutch forum I'm in discussion with a crackpot about extracting energy out of a magnet. He claims that when a iron object enter the range of a permanent magnet it need energie to become ferromagnetic. Is this really so and if it is where comes the energy from?
  36. Kerrie

    Men: Knitting makes you a babe magnet.

    http://www.kgw.com/lifestyle/stories/kgw_020405_life_men_knit.715d1831.html I think this is absolutely terrific. Of course, some guys wouldn't think so.
  37. W

    Solving Magnet Problems: Minimum Magnetic Field for Horizontal Northward Motion

    I am having too hard of a time with such a simple magnet equation that I am starting to loose it. A particle with a mass of m carries a negative charge of - q. The particle is given an initial horizontal velocity that is due north and has a magnitude of v. What is the magnitude of the...
  38. C

    Spining Sphere magnet inside rim of coils how do u calculate voltage

    Can we please imagine that a sphere Neodymiun magnet with a diameter of one inch was suspended or leviated, reducing friction to none, then we put this magnet inside an acrylic tube that created a vacuum by pumping out all the air out allowing the sphere to spin at enormous velocity with very...
  39. BasketDaN

    Maximum pull a of normal magnet

    What is the maximum pull a normal magnet (non electromagnet) of about the size of a computer mouse could achieve? And how would the cost of this compare to the cost of an electromagnet of the same pull? Also, will an electromagnet achieve it's desired pull immediately when the circuit is...
  40. B

    The Truth: The Relationship Between Magnets and Free Energy

    magnet and free energy when i stick a magnet on a fridge it willl eventually slide down and fall of due the domains in the mganet nuetralizing each other out right ? Now my question is does the energy reuiqred to realign the the magnet to its original strength = the amount of enrgy that is...
  41. S

    How does a permanent magnet lift iron filings

    Evryone knows that the work done by a magnetic field is zero. Then how does a permanent magnet lift iron filings.
  42. holly

    Why is a magnet broken in half still as magnetic as the original?

    Q. A rectangular bar magnet is broken in half longways. The resulting pieces are: Answer: as magnetic as the original magnet. I don't see why it isn't half as magnetic. I broke one of my fridge magnets in half, and I'm tellling you, it's only half as strong now. It can't hold the recipe up...
  43. I

    Antenna and Magnet: A Curious Explorer's Tale

    I am aware of the apperent presence of electrons on the [flat, top] base of an antenna such as one on a radio. I took the time to obtain a magnet with moderate strength. I placed the magnet about a centimeter away from the [flat] base of the antenna and found it vibrated. As I decreased the...
  44. U

    Electricity Generated by Magnet Motion Over Coil

    A small coil is laid on a flat table and a magnet is held vertically over the magnet. Both are stationary. I move the magnet so that it passes the coil and then held it stationary again. I move the magnet over the coil and hold it stationary there again. What am I supposed to conclude about the...
  45. C

    Designing an Experiment: Varying Magnet Temperature & Field Strength

    am to design an experiment showing how magnetic field strength of a magnet varies with its temperature. i know i can use a hall probe to measure the field strength - but how do i vary the temperature, and ensure that this is uniform throughout the magnet?
  46. C

    Designing an Experiment: Varying Magnet Temperature and Field Strength

    i am to design an experiment showing how magnetic field strength of a magnet varies with its temperature. i know i can use a hall probe to measure the field strength - but how do i vary the temperature, and ensure that this is uniform throughout the magnet?
  47. J

    Understanding the Fundamentals of Magnetism: How a Magnet Works Explained

    newbie here - i know this question is tangled up with the question, "what is a field?" and "how does a field work?", but to keep it simple (ha!) can someone please try to explain how a magnet works? ie, how is force transmitted from the magnet to its surroundings? does a magnet "do work"...
  48. J

    Conducter in magnet fild - curent

    I can't get it imy head why are electrons set in motion in magnet fild - that changes, or why do they move in not strait motion in stady magnetic fild. I know about Lorentz force, but i don't know why, and why that specific direction? I've tryed to correlate it to electrons magnetic fild...
  49. eagleone

    Permanent Magnet Shape: Position of N/S Poles

    Let’s say I make ball (sphere) out of permanent magnet material. Where will be N/S poles, will they take fixed position or, as I think, position won't be fixed. p.s. same for magnet ring
  50. C

    Permanent Magnet Pump Speed Control

    Hi, I have a submerged magnetic water pump that is pushing too much water at 8500L/hr. I know that the propeller rpm depends on the frequency of the AC supply but how can I build a simple circuit to reduce the frequency? Thanks :smile:
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