What is Electromagnet: Definition and 371 Discussions

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole, denoting the center of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.
Electromagnets are widely used as components of other electrical devices, such as motors, generators, electromechanical solenoids, relays, loudspeakers, hard disks, MRI machines, scientific instruments, and magnetic separation equipment. Electromagnets are also employed in industry for picking up and moving heavy iron objects such as scrap iron and steel.

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  1. T

    I have a electromagnet with 200# pull is their a way to get full pull

    i have a electromagnet with 200# pull is their a way to get full pull on sheetmetal or is their something i can do to the sheetmetal.
  2. N

    Exploring Electromagnets: Understanding Vibration and Humming Phenomenon

    Hello, I have a question from some playing i was doing with an electromagnet. I made a simple electromagnet out of a nail and some small gauge wire (not sure of the gauge). I wrapped another nail with some un-insulated wire of the same gauge and left it un-connected to any power supply. I...
  3. K

    Can a lift electromagnet pull a permanent magnet?

    A lift electromagnet has N + S pole on the same side. will it push or pull a permanent magnet which has N & S pole on opposite side? If I have a lift electromagnet and a permanent magnet, both can pull 100 lbs. What is the break away force if I put them together? Thanks
  4. S

    Can a Simple Electromagnet Lift Tuna Cans?

    I need to build an electromagnet that is able to pick up 8 ounces from 2-3 inches below it. the tuna cans are magnetic and are full of tuna. I have limited funds but have a lot of wire and stuff at home. the electromagnet will be powered at approx. 7.4 volts. i would like the electromagnet to be...
  5. S

    Electromagnet with lowest energisation times.

    Hi there PF, I am currently trying to make an electromagnet that is able to turn on and off at about 2-4Hz of frequency and is able to repel small neodymium magnets with about 16N of pull force. I have tried various configurations of coils around ferrite cores. The power supply has been...
  6. N

    EMF of an AC carrying electromagnet.

    Homework Statement This problem arises from a much larger essay/lab/project thing. I know that there is an induced current in the wire of an AC electromagnet because the magnetic field is constantly changing along with the AC current, so it makes sense to me that will produce a constantly...
  7. U

    Help with electromagnet design

    Hi everybody, I just had 100m of copper winding wire arrive in the mail so I can build an electromagnet. I'm aiming to pull a 5kg weight along, which is already floating on a separate magnetic field so all friction is removed except air resistance. What I want to do is put an...
  8. S

    Calculating the force between a magnet and an electromagnet

    Hello. I would just like to begin by saying that I am very aware of the vast complexity of the subject of magnetism. Still, I have been hoping to find a way to get a basic idea of how much a magnet and an electromagnet are attracted or repelled by one another. I do not need highly perfect and...
  9. P

    Make an Electromagnet Stronger: Tips & Ideas

    hi i I'm doing a science fair project on how to make electromagnets stronger and i was wondering if you guys could answer some questions. first of all i need to find a good place to buy an iron core preferebly not online, i live in sandy utah in the united states. second i was wondering if you...
  10. G

    What is the difference between permanent magnet fields and electromagnet fields?

    What is the difference between permanent magnet fields and electromagnet fields?
  11. C

    Electromagnet with and without airgap.

    Hello! I'm a bit confused by a phenomenon regarding electromagnets with and without airgaps. A picture of the kind of electromagnet i have in mind is found here: http://sci-toys.com/scitoys/scitoys/magnets/calculating/calculating.html If one has a "loopy" electromagnet without an...
  12. P

    How Does the Length of a Yoke Affect the Inductance of Yoked Coils in Series?

    When finding for "L" is the value for "l" (length of coil) affected by the length of the core material. Or more specifically when one is working this equation for two coils yoked in series do you figure each coil separately?...and if NOT, do you include the length of the yoke? Here is a link...
  13. B

    Tracking Wire Position with Electromagnet & Permanent Magnet

    I am trying to come up with a design that would track the position of a wire. The wire will have a permanent magnet attached to its tip. I will use a electromagnet to move the wire in only 1 dimension. Here is what I was thinking... I would put a stationary aluminum plate some distance from...
  14. D

    Electrical Permanent / Electromagnet DIY Query

    To make your own electromagnet simply use an iron nail wrap some copper wiring around it and tape it to a battery fair enough, the current passing through the wire causes a magnetic field... My question is one of annoyance because my boss won't let me try it with the 100mm Neodymium magnets...
  15. F

    Building an Electromagnet for a Unique Hourglass Project

    I am starting a rather unique project and thought I would ask a few questions before I get too lost. Basically the project is to create an hour glass that can be controlled so the sand will go both down or up. My first thoughts were to use a series of electromagnets in a pulse series to lift the...
  16. I_am_learning

    Design Powerful Electromagnet: Maximize Magnetic Field w/Constant Power

    I am trying to design a very powerful electromagnet for experimental reasons. However, I am wondering at his absurd sounding conclusion I arrived at! The governing equation of the magnetic field generated by a solenoidal electromagnet is B = u0nI Provided that I keep these things constant 1...
  17. B

    How much force can a 1000 lb electromagnet pull at 4-6 inches?

    I was inquiring about how much force will a 1000 lb pull force electromagnet pull at 4-6 inches away from the magnet
  18. O

    Relationship to determine the lifting capacity of an electromagnet

    Homework Statement To determine a formula that can be used to determine the lifting capacity of an electromagnet/magnet through a known air gap. Homework Equations Weight= (magnetomotive force)/reluctance The Attempt at a Solution From the experiment the following general...
  19. C

    How Does Changing Current and Coil Loops Affect Electromagnet Lifting Force?

    Homework Statement A coil with an iron coil is used as an electromagnet. With 500 loops and a current of 1.5A, it can exert a lifting force of 30N. What force would it be able to lift, if the following changes were made? a) The current is increased to 3.0A. b) The number of loops is...
  20. R

    Problems with electromagnet force and weak force

    The electromagnetic force is mediated by photons , which have 0 mass. so electromagnetic forces have infinite range. the weak force is mediated by three intermediate bosons, W+, W-and Z0 particles. these all have mass, the two W particles about 80GeV and the Z is about 90GeV. the bit below is...
  21. JJBladester

    Electromagnet within a coil

    Homework Statement Hooking up voltage to a solenoid (coil of wire) creates an electromagnet. Moving the electromagnet in and out of a larger coil hooked up to a galvanometer creates an emf (voltage) in the larger current. Does an emf get created for a *stationary* electromagnet inside a...
  22. V

    Why does an Electromagnet Vibrate ?

    Why does an Electromagnet Vibrate ? whenever any iron plate or steel spoon is placed near permanent magnet(not of very high strength) it gets attracted towards it and when it is removed from it it removes easily without any vibration effects. but if the same thing is performed with...
  23. F

    Electromagnet to repel neodymium magnet?

    Hello all! I'm new to this site and new to electromagnets. I've done some research but now i need help from anyone who is willing. I'm playing around with electromagnets and neodymium magnets. Now i want the electromagnet to repel the neodymium. So first thing I can't use a ferrous material...
  24. J

    Need help understanding off axis electromagnet field strength equation

    I have this equation for the magnetic field strength of an electromagnet but it’s in the form of multiple polynomials. Here is the page where they all are: http://www.netdenizen.com/emagnet/offaxis/solenoidoffaxis.htm since it gives values for e_8 and p_8 I tried using the main equation up...
  25. A

    Repulsive force btwn electromagnet and permenant magnet (NdFeB)

    hi all, i am currently working on a magnet generator/motor and i have some qns on electromagnetism. i am currently trying to find out how much does my electromagnet (ferrite core) requires in order to repel a permenant magnet, in this case, a cylindrical NdFeB magnet. i have been trying to...
  26. A

    Force btwn an electromagnet and a permenant magnet

    hi all, i am currently working on a magnet generator/motor and i have some qns on electromagnetism. i am currently trying to find out how much does my electromagnet (ferrite core) requires in order to repel a permenant magnet, in this case, a cylindrical NdFeB magnet. i have been trying to...
  27. T

    Is it practical to make an electromagnet that causes a 200N force?

    I'm trying to construct an electromagnet that, when a loose piece of iron is inside the solenoid, will create a field that will attract that piece of iron with at least 200N of force. My thought is that I can fill half of the solenoid with an iron core, leaving space in the other half for the...
  28. A

    Using an Electromagnet with a switch?

    I'm making an electromagnet for a contraption. As far as I know all the electromagnets demonstrated on the web are working permanently with supply of battery (Direct current). I need to know how i could make an electromagnet which works on an AC supply with a switch ? Please provide some...
  29. A

    Power Supply Alternatives for an Electromagnet

    Homework Statement For an electromagnet that is just made up of wires and a core, what power supply can I use other than batteries that let me adjust the volts? Can you explian in detail? Homework Equations none The Attempt at a Solution I have already looked on the...
  30. H

    A nail is placed inside an electromagnet, why do we feel a buzzing sensation?

    Homework Statement A nail is placed inside an electromagnet, why do we feel a buzzing sensation? Homework Equations The Attempt at a Solution Is it because of resonance? Can someone please explain? Thanks!
  31. B

    Magnetic field energy and force of an electromagnet

    I'm reading up on the equations for electromagnets, and in looking over the Wikipedia page on the subject I'm wondering if it's in error or if there is a flaw in my understanding. Specifically, it says that the force exerted by a magnetic field in an electromagnet on a section of core material...
  32. B

    Electromagnet coil core to yoke ratio?

    I'm building pairs of coils with standard core heights and diameters and linking each pair with a yoke. The magnets all run at 6V DC with windings of 24 AWG magnet wire in 6/8/10 layers. Is there a ratio of coil core mass to yoke mass for maximum efficiency? (shown below)
  33. R

    Why is my electromagnet not producing any current?

    Dear Guru Engineers, I made 650 coils round a ferrite rod of cirumference about 2cm using super thin (like hair) copper wire that is insulated by some kind of yellowish golden orangy 'lacquer'. I hope you get the picture what i am trying to describe here :p Anyways, i used a strong magnet...
  34. A

    Help me Modify 11th grade Electromagnet project

    Homework Statement I'm in 11th grade and I'm in an honors physics class. Everyone has to do a science fair project and the teacher said that mine is too easy. Mine is which of the following factors affects the strength of an electromagnet the most: # of coils, thickness of the wire, the...
  35. L

    Design 1T Solenoidal Electromagnet w/ Core Permeability>1000

    I was trying to get the numbers to design a 1T solenoidal electromagnet with a core of permeability >1000 (electric steel or Permalloy). I think the permeability saturates at some field strength(0.2T?). But I am not sure how to use the formula after saturation. should I just use u0 instead of...
  36. S

    ElectroMagnet Suspension Project

    Does anyone know where i can source ferrous iron (rod or bar) from in the UK? This is for a Third Year university project Approx dimensions: 25mm diameter by 300mm long Thanks In Advance Alex
  37. M

    Using a magnetic core for an electromagnet

    Hi, I would like to know what would happen if you used a permanent magnet for the core of an electromagnet, instead of the standard ferromagnetic core? Can you increase the magnetic field strength of the permanent magnet by putting current through the coil? Also, could you effectively...
  38. N

    Electromagnet, and unanswered questions

    Hello All, My name is Nik. I am very glad I found this forum. For the past couple months i have been researching (YES, I do use the search function) information on electromagnets. I have done a lot of reading on wiki so I am familiar with its E.M. page. I am building an electromagnet. Like...
  39. A

    Creating a Lightweight but Powerful Electromagnet

    Yesterday I was using a riding a lawnmower and the bolt that held the float bowl fell off in deep grass. I looked for about 15 minutes when I seen a flash of lightning and I figured I better give up searching and start pushing this thing back to the house. This experience made me wish I had a...
  40. T

    Would super-conducting of space itself create electromagnet fields?

    Note, that I'm just asking for opinion. I do not fully know everything about everything - I am still in school and I am yet to develop the never-ending knowledge that you guys on here posses. Would super-conducting of space itself create electromagnet fields? Space in the context is being...
  41. D

    Can an Electromagnet Stop a Speeding Vehicle?

    Hello everyone, I just joined the forum because my friends and I have been having an argument for a couple hours now over magnetism and its uses. So I will just jump right into our argument... I say that an electromagnet attached to the front bumper of a vehicle can be attached to the...
  42. Y

    How Does Frequency Affect the Strength of an Electromagnet?

    I am looking for a relation between electromagnet (or permanent magnet) and frequency.For example what is the frequency of an electromagnet that has 45000 gauss electromagnetic field? Thanks.
  43. N

    Help with building an ElectroMagnet

    I have been looking through the forum for help on working out what i would need to build an electromagnet to certain specifications, but as i have not done anymore than a grade nine level physics frankly I don't understand most of what's in the posts. So if you reply can you break the physics...
  44. E

    Advice on building a 1.4T electromagnet

    I'm trying to build a C or H-frame electromagnet that produces a flux of 1.4T in the gap between its two poles. (See: http://cyclotron.lbl.gov/images/Cyclotron%20yoke.JPG ) But I can't find any references on building C/H-frame electromagnets. I calculated with permittivity of free space...
  45. S

    How Do You Design an Electromagnet to Attract a Disk from 15cm Away?

    Hello, I need to build an electromagnet in order to pull a disk magnet from a distance of a 15cm. I don't know how many turns and how large to make the electromagnet. I need it to be in the shape of a solenoid. What are the formulas needed in order to do this? Thanks in advance, Shay
  46. B

    Residual electromagnet magnetism

    Have always wondered this so maybe I can get an answer here: when a large industrial electromagnet is switched off and the electricity-produced magnetism ceases, is there a small amount of residual magnetism in the uncharged electro-magnet? If so, does it dissipate according to a established...
  47. U

    Can a Rechargeable Electromagnet Be Created Using a Capacitor and Battery?

    I was wondering if it is possible to make a rechargeable electromagnet like this: http://artpad.art.com/?kmhzngmfdqo Please bear with me as I have poor drawing skills. :grin: It consists of a capacitor, 9V battery, and a electromagnet. Will it work?
  48. C

    Troubleshooting Electromagnet Design for Telegraph Key and Sounder

    I'm trying to build a telegraph key and sounder. The sounder that I have designed (well, saw online) is a metal nail (which is ferromagnetic) with at least several dozen (maybe 200+) turns of wire around it. When a current is on the wire, the nail should become an electromagnet, and then pull...
  49. J

    Electromagnet Materials: Can They Stay Magnetized After Current is Switched Off?

    Hi everyone, Is there a material which, inside a solenoid, immediately or in a very short period of time gets magnetized as current is switched on and then stays magnetized for a while if the current is switched off? For if this were true then this would mean we could derive more energy out of...
  50. B

    North and south pole in an electromagnet

    Not sure if this should be in engineering or physics section. Sorry if I got it wrong. How do I determine the north and south pole in an electromagnet? Do electromagnets have a constant N or S pole? I am making a locking device where a neo magnet will hold a lid down tightly by sticking...
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