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. N

    Force exerted by Ferro-magnetic Electromagnet

    I've been confused for awhile about this and I haven't found any decent explanatory answers. I read somewhere that the general formula for finding the force exerted by a solenoid electromagnet could be found by: Force = ((N x I)^2 x k x A) / (2 x s^2) where N is number of turns of a...
  2. B

    What knowledge is needed for Electromagnet design?

    guys, I want to design a electromagnet. but i do not know how to start. so could you please tell me what knowledge is needed for electromagnet design? Or you can recommed some data that i can find and buy myself. thanks in advance!
  3. E

    Electromagnet Design - Value of inductance L

    Homework Statement Hi all, I am working on an electromagnet design. It is a C-shape with an air gap of 80mm. The number of coil windings is 320 turns. I would like to generate let's say B = 30 mT = 300 gauss in the air gap. Area of air gap Ag = 80mmX80mm = 6.4e-3. Mean length lg of...
  4. K

    Electromagnet construction and off-axis field calculation with iron core

    Hi, I'm wondering if anyone has any sources for off-axis point calculation for multiple current carrying loops that contain a soft iron core. I have been using this resource so far and I can figure out how to include multiple loops. How would I approach these calculations with an iron core...
  5. A

    Electromagnetic Energy: Learn the Basics

    Electromagnet energy ? Hi i have very little knowledge of electrodynamics so this is probably a no brainer but: Given an electromagnet holding a ferrous mass suspended in gravity is the electric energy required exactly equivalent to the basis draw with no mass load?? Thanks
  6. D

    Electromagnet: How to build the right one?

    Hi there! I hope someone can help me ... I'm trying to build an electromagnet to use in a system inspired by Bob Beck and electro-medicine. I have a friend building me a circuit to generate a pulsed wave to drive an electromagnet. It's my job to build the electromagnet, but after several...
  7. O

    How many turns in my electromagnet?

    Hi, I am making a DIY electromagnet. I'm using 2 9v D Cell Batteries as the power source and a 15mm diameter iron core. I am looking to make the magnet as powerful as possible. My questions are as follows: 1. Should I connect the batteries in series or parallel? 2. What gauge...
  8. J

    Electromagnet project - questions

    Hey. I'm doing a summative project for my physics class in which I'll build a fairly strong electromagnet and see how different amounts of current affects the force it's able to exert. A few questions: What is the best core material to use? Also, does it matter what I use to separate the coil...
  9. K

    Exploring the Strength of an Electromagnet with a Permanent Magnet Core

    I have another question, what would happen if i used a cylindrical permanent magnet as the core for an electromagnet. Assuming the poles of the solenoid are in matching direction, will the magnet field be stronger? What happens if the poles of the solenoid are in conflicting directions with...
  10. K

    How to calculate the repulsion force between a permanent and an electromagnet?

    Both the permanent and electromagnet will be constrained within a cylindrical tube (both magnets will be of cylindrical shaped, and have more/less the same cross sectional area). I want to know if its possible to calculate the repulsion force, in lbs, between the magnets, with a distance...
  11. wolfspirit

    Electromagnet core dereference between hard and soft iron

    in terms of what buying what is the dereference between hard and soft iron? i know an iron core is good but what about cast iron?
  12. wolfspirit

    Power supply for electromagnet

    hi i am wanting to make an electromagnet as a project and i have ordered 916 meters of 0.125mm ENAMELLED COPPER MAGNET WIRE. i am a electronics hobbyist but i have not played with bench top power supply's before and i don't know where to start what is the best/ safest or how to use them...
  13. S

    Quick electromagnet coil question

    Hello everyone I have coiled an electromagnet over the weekend using iron and magnet wire, but when I connect it to my power source, the electromagnet becomes very hot. Is there some coating I can use to reduce the heat produced by the electromagnet when in use? Like epoxy or some sort of...
  14. J

    Optimal electromagnet bobbin material

    I can't seem to find any answers on this...I'm experimenting with some electromagnet designs, but I'm not sure what the best bobbin, or end caps would be. I was thinking about using steel washers welded to the iron core since it would be the strongest, but I thought that may affect the EM field...
  15. Y

    What size does electromagnet has to be to imitate the power of neodymium magnet?

    Hello all, I am interface designer that occasionally steps out and does some product/concept design. The last one I am working on is something that would require me to make a matrix of little electro magnets, and i am just starting to inform my self about all that. I loved electrical...
  16. R

    Electromagnet Design Help Required

    G’day everyone I need some direction / advice in the area of electromagnet design. Application and restrictions: DC supply Push down and hold with 100N of force Pull up with 100N of force and hold with 1,000N of force (or pull up and hold with 1,000N of force) Stroke length: 10mm...
  17. A

    Calculating the number of turns and thickness of an electromagnet

    I'm working on a homemade electromagnet, to use on my racecar :biggrin: I want to calculate the number of turns of an electromagnet and the thickness of the wire. But i have tried to search arround in books, and can't really find any thing. I know my wire is 0,114mm and dimensions for...
  18. T

    Electromagnet stick is the key to build a flying disk

    The electromagnet stick always head N/s, no matter how fast the rotation of the shell of the disk is, you just need to control the input voltage of it, and it will not get heavy if the Magnetic stronger. I think the input higher voltage can make it head with power and hard to change the...
  19. R

    Building a more powerful electromagnet

    Hey so I'm trying to build a few poweful electromagnets and I need some help because i don't really know much about the topic. What gives an electromagnet more power? Number of wire turns? Multiple layers of wire turns? Is it amps or volts that gives them their drive? Also what's the best gauge...
  20. Y

    Made an electromagnet, curious about how this works exactly.

    Hi, I'm a sophmore in high school, and I haven't taken the Physics course yet. So I'm a bit green. Anyway, I was playing around with an electromagnet I made with a nail and some 1mm wire, and I've got a few questions about the magnetism it generates: -First, why does that iron core need to be...
  21. T

    Core material for electromagnet that doesn't oxidize

    Does anyone know of any electromagnetic core materials that either do not oxidize or who's magnetic and physical strength doesn't change much when it does oxidize? I need to make a room temperature electromagnet for hydrodynamic propulsion experiments. My first experiments used an air core but...
  22. G

    Well I need to create a reasonably powerful electromagnet and I am in

    Well I need to create a reasonably powerful electromagnet and I am in Gr. 12. I havn't been able to find a proper guide/book to create a electromagnet. I plan on using a ferrous core and 38 gauge wire. I am going to wind the wire around a spool. My questions: What should be the diameter and...
  23. D

    Why Does Voltage Versus Energy Exchange in an Electromagnet Show a Linear Trend?

    In order to determine the temperature that an electromagnet reached after a 3 minute period the electromagnet was placed in a constant volume of water. After 3 minutes the change in temperature of the water was measured and from this using the equation Q=mcΔT the energy in joules transferred...
  24. U

    Building an electromagnet hover-coaster

    Want to know the posibilities of lifting over 300Kgs How much current will be required of electromagnets holding the coaster carriage lifted above two beams on either side? Also will it work to place electromagnets on opposing sides (top and bottom, left and right) of the beam to hold the...
  25. B

    How can I create a symmetrical electromagnetic field with two cylindrical poles?

    Greetings. I need help making an electromagnet. I would make it out of copper coil and a rare Earth metal, undecided on that point yet. I know how to make a basic one but this one has to have two (2) cylindrical poles, that would remain vertical above each other. It cannot be a horseshoe magnet...
  26. T

    How Can I Increase the Flux Density of My Electromagnet?

    Hi, I am trying to design an electromagnet. I am utilising the lorentz force equation to develop the force. i.e. F= BIL. The problem is I can't increase value of B beyond 1 tesla as the core saturates. Also high current is not feasible. Can anyone suggest how to increase the value of...
  27. M

    Small Electromagnet for High School Show Effect

    Hi, I am new to this forum and not a physicist by any means. I am a high school music teacher working on a special effect for our upcoming show. Long story short, I need the bird to fall off of its perch on a cuckoo clock, and it needs to happen on cue (one of the characters shoots the bird...
  28. R

    Build Powerful Electromagnet: Wire or Bitter Plates?

    I am needing to build an electromagnet that will sit around part of a torus. In your opinion would I be better off just using wire to wind my own electromagnet or making bitter plates that make an electromagnet? I realize this might sounds crazy but I need to build a very powerful...
  29. B

    Electromagnet Design Questions

    Hey guys, so I have a couple questions about electromagnets that I was hoping to get some insight on here. Basically, I've been tasked with designing an electromagnet that is low-heat (<150F or so) yet high pull force. I'm improving on a past design where the electromagnet got way too hot (>...
  30. T

    Understanding Electromagnets: Unraveling the Mystery of North and South Poles"

    So I have a question about an electromagnet. I understand the right hand rule, and how the magnetic field wraps around the wire, but I don't understand the location of the north and south poles. How do you determine where the north and south poles are since the magnetic field is a circle around...
  31. I

    Electromagnet for attracting Non-ferrous metals

    Good morning: I'm looking for information on electromagnets for attracting non-ferrous metals. One of the kids on the block is asking for assistance in research for a science fair project. She has a 1951 pamphlet describing the effect. And I found a construction article, but very little...
  32. P

    Characterise Magnetic Field Outside Electromagnet core

    Hi all. I am shortly to begin work on my engineering FYP in automatic control and I'm hoping for some advice to point me in the right direction. The project will initially be an electromagnetic suspension rig (cylindrical winding with soft core suspending a permanent magnet below it via...
  33. J

    Need Help With Large Electromagnet Design

    Hello Everyone. I'm very new to this website and am turning to anyone for help. I'm trying to design and build a large electromagnet to do some scrap metal lifting for me and my grandpa that can be hooked onto a crane/loader of a tractor/payloader. I'm currently studying electrical and...
  34. K

    An electromagnet made of a bunch of capacitor plates in series?

    Has anyone every tried to make an inductor made out of capacitors, that is to say, which uses the magnetic field of displacement current rather than that of electron current to generate magnetic fields? Let's say the gap between plates is greater than the thickness of each plate. Wouldn't most...
  35. O

    Can you magnetise an iron sheet with an electromagnet?

    This is kinda related to my other thread, but I thought I'll make another one. So, can you magnetise an iron sheet with an electromagnet? Does the electromagnet have to be touching the iron sheet or can it just be near it? Does the thickness of the sheet metal affect its magnetic field...
  36. O

    Should I bother making an electromagnet or just use neodymium for my motor?

    Okay, so I need to make a DC motor for my physics assie and I am aiming to use an electromagnet to magnetise iron sheets shaped into the shape of a radial magnet. Would this even work? O.o Or would neodymium be better for its size? How large would the electromagnet have to be in order to beat...
  37. R

    Help with Electromagnet Project Design

    I was referd to this forum from a friend and I have been reading some of them and I think you guys can help me and I would be very happy if you could. I was taking a electormagnitism physics class in school, calc based, and I had this idea for a project. I know that to calculate the magnetic...
  38. E

    Can a block of aluminum become an electromagnet?

    So I have this huge solid cylinder of aluminum about a foot tall, and 2-3 inches in diameter. I understand that aluminum is not a permanent magnet. But it DOES conduct electricity. So, if I wrapped a conductor around it, and hooked that up to a power source, would the aluminum become an...
  39. T

    Comparing Strength of Electromagnets and Neodymium Magnets at 4 oz and 12v

    Which one is stronger given they are the same size and weight? Say 4 oz. Just say you only have 12v to work with on the electromagnet.
  40. Y

    Advice needed on Electromagnet specifications

    I have about 300 metric tons Iron Filings as per attached representative photo in a godown. Mixed with small percentage of Aluminum. I need to separate the Iron filings and Aluminum. Separated Iron Filings need to be straightaway loaded onto a truck. Godown entrance is about 4...
  41. T

    Magnetic Field Strength of an Electromagnet given variable currents

    I had a lab to do for Physics, and we used a variable voltage source and an electromagnet with 60 turns of copper wire. What is the equation to use to find the magnetic field strength B using relative permeability of a soft iron core? i cannot find this equation anywhere... plus, what is the...
  42. S

    Calculating the strength needed for each electromagnet in a stepper motor

    I am designing a stepper motor, and I need someone to check my calculations. The results seem impossibly low... Suppose the vehicle driven by the motor is already up to speed. The force needed to maintain that speed are, say, 100 Newtons. At the speed, the stepper motor performs 15,000...
  43. M

    Electromagnet offset between applied voltage and magnetic field intensity

    I'm trying to find a mathematical formula between applied tension and resulted magnetic field intensity on an electromagnet. I know that between the voltage and the electric current there is a pi/2 offset, but in practice there is a bit more than actually pi/2 offset probably something that...
  44. H

    Electromagnet investigation lab assignment

    Homework Statement An alpha particle enters a uniform verical magnetic field of 1.0 T with a velocity of 2.0m/s East. a) Find the force exerted on the particle by the field. b) Find the acceleration of the particle. c) Find the radius of curvature of the path of the particle. Homework...
  45. N

    Controlling Timing of Electric Pulses to Electromagnets

    Hi all, just came across the forum and I must say I am in heaven, great site! I am trying to figure a way to control the timing of electric pulses to an array of electromagnets... some in the array need to just be controlled for standard on/off function, while others need to have control over...
  46. L

    Need help/advise with building an electromagnet

    Hello. I'm looking for some assistance with building an electromagnet. Was going to just build it, but want to be on a safe side =)... Due to my chronic Lyme Dis. did forget somethings, and being a son of electrician doesn't really qualify me as an electric engineer. Have googled but came...
  47. D

    Quick release latch using an electromagnet

    I am currently working on a quick release latch that is using an electromagnet to open the latch. I currently have a spring attached to a bolt latch. I would like the electromagnet to be able to counter the force of the spring opening the latch. the force of the spring is about 9 Newtons...
  48. H

    Dynamo to charge battery using electromagnet.

    Homework Statement A team on The Apprentice have to come up with a new electrical device. They propose a hand cranked dynamo to charge a battery which initially uses the residual charge in the battery to power the electromagnet, instead of a permanent magnet (the idea being that this...
  49. M

    Question about magnetic fields (electromagnet)

    Hi guys, So far I am aware of these rules regarding magnetic fields/direction of current: A compass needle point is attracted to a south pole (or inversely repelled by a north pole). Left hand rule #2: For an electromagnet, point thumb toward north pole, fingers curl in direction of current...
  50. P

    Magnetic forces required to repel, one permanente and one electromagnet

    Hi guys, this is my first time here. I'm currently working on a new design, our team works for Network Rail and we really need your help. Ok here's the problem: I have a magnet, permanent magnet which is able to move only up and down, not laterally. I have another magnet, this time its an...
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