# 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.

View More On Wikipedia.org
1. ### B Changing magnetic polarity of an electromagnet

I would like to change the polarity of an electromagnet. I have reversed the wires attached to a 9 volt battery that wound about a bar magnet but this did not seem to make the north pole become the south pole. Thanks for your assistance, Frank
2. ### Electrical Electromagnetic confinement and Oscillators

I am wondering if it is possible to use two electromagnets oscillating at about 1 ghz to suspend an amount of ferrofluid in an acrylic chamber. As I understand it, 1 ghz should be sufficient enough to get the ferrofluid away from each magnet, as after a quick google search, magnetic fields move...
3. ### Find v and x of electron in an electromagnetic wave

When dv/dt= -qE/m(sin(ωt+φ)) Find v Then x By integrating
4. ### Electromagnet Polarity Switching for Reversed Motion

I am trying to understand the differences in design between a traditional solenoid with a ferrous plunger vs linear motors that use either induction or permanent magnets. From my understanding, a traditional solenoid, whether DC or AC, cannot fire in both directions with polarity switching since...
5. ### I Electromagnet on Starship Orion

Can an electromagnet push the ship forward by absorbing the momentum of a nuclear explosion via a magnetic field? Im thinking this will solve the problem of constantly having to repair the eroding plate if its replaced by a magnetic field sustained by a fission reactor generating power...
6. ### Compressor driven by an electromagnet

Figures: Attempt at a Solution: $$L=0,015\, \textrm{m}\qquad R_2=0,01\, \textrm{m}$$ $$R_1-R_2=R_D=0,0075\, \textrm{m}$$ $$L=0,04$$ $$\rho_1=\dfrac{p_1}{R^2T_1}=\dfrac{p_1\bar{M}}{RT_1}=1,164\, \textrm{kg}/\textrm{m}^3$$ Calculate total volume ##V_A+V_B##: V_B=\pi \cdot R_2^2\cdot...
7. ### I Force exerted by an iron core electromagnet on a ferrofluid

I am trying more generally to find the equation of the fore exerted by an electromagnet. The one that I keep finding is F=((NI)^2 A mu0)/2X^2. N is turn number, I is current, Mu0 is permeability of free space, A is the area of the core and X is the distance from the electromagnet. I take...
8. ### I Why is my magnetic levitation experiment not working?

[Mentor Note -- Two similar thread starts merged into one] Hey all, I have been working on this project for a while now, which features suspending an object midair through the use of magnetic levitation principles. Cool right? And so I have been researching and trying, even finding ground...
9. ### Magnetism / Electromagnet Levitation question

I can make one magnet ‘leap’ up to another magnet and I can push one magnet away with another magnet but can’t figure out how to do both at the same time so the first magnet can essentially be suspended in mid air with the controlling magnet being above. Any thoughts are appreciated. Thanks
10. ### Is it Possible to Create a Large but Low-Powered Electromagnet?

Hi to everyone! I'm currently working on a University project and one of my crazy ideas needs me to get my hands on a pretty strange electromagnet. the measurements are 40cm by 40cm with a height of 3 to 5 cm (doesnt matter a lot) i don't need this magnet to be very powerful (just enough to...
11. ### B field around a wire, single wire electromagnet

A quick description. A single straight wire and a second straight wire, both wires are electrically as well as physically separated, the physical separation distance assume is very small in order for the B field experienced by the second wire to be sufficiently strong. In all cases one of the...
12. ### Engineering Magnetic field strength of an electromagnet (coil wound around a bobbin)

I am trying to design an electromagnet which consists of a copper PVC sheathed wire wound around a cylindrical plastic spool of Circumference (C) = pi x diameter. The spool has a hollow body of diameter D1. This wire has maximum length (L), cross sectional area A, resistivity P. The spool once...
13. ### Can a superconductor "repel" an electromagnet due to the Meissner effect?

A superconductor with little or no magnetic field within it is said to be in the Meissner state. The Meissner state breaks down when the applied magnetic field is too strong. But what happens if an electromagnet that is at first "turned off" is suddenly "turned on", in the close proximity of a...
14. ### What is the strength of this scrap yard electromagnet?

I have a dc magnet which use in scrap yard and the only perameter I know is ,it consume 50 to 70 amps and it area , 440 ac input supply .now I want to know how iron scrap it can lift?
15. ### Maximizing Repulsive Force with an Electromagnet

Hi all. New to the forum and new to making electromagnets. I want to pick your brains as I know extremely little about electromagnets. So I have a 2 1/2 inch round x 1 inch thick rare Earth magnet that I’m trying to repel with force using an electro magnet. The repel would be in bursts. I know...
16. ### Electromagnet Coil Performing Poorly

I recently posted about an air cored electromagnet I was designing. It currently uses 300' of 17 AWG magnet wire, coiled around a .5'' diameter tube. I purchased a DC to DC step up to test different voltages and currents. I noticed while using it that regardless of what current I supplied...
17. ### I have been trying to create an air-core electromagnet with no luck

The magnet I have been created has been coiled around an aluminum tube. This tube has an OD of .5'' and an ID of .375''. This leaves 0.125'' as the thickness of the aluminum. The electromagnet was created with 17 AWG magnet wire. This wire is 157'long and has a diameter of 0.0469''. It is...
18. ### Zeeman effect: Experimental Setup and Explanation

Homework Statement: Hello, I have to explain using numbers the Zeeman effect for hydrogen and the setup needed. I have done some research and if I'm not wrong, then a magnetic field of 1 Tesla is needed. I have no idea how to achieve that using commercially available products and how to even...
19. ### Theoretical question about an electromagnet in an AC circuit

This may be a stupid question, but here is what I am asking. Using a very simple circuit, say 120v AC water heating element rated at 1000 watts meaning 120v AC hot leg on 1 terminal and a neutral on the other terminal. That would give 8.3 amps of current, meaning the resistance would be 14.4...
20. ### How to calculate the reluctance of an electromagnet

How do you calculate the reluctance of An electromagnet that consist of a nail with bare copper wire wrapped around it? I have tried searching on the internet. Have not found a website that answers my question. Not wikipedia or any other website.
21. M

### Electromagnet that can generate 100 lbs at small size

I wondering if it is possible to create an electromagnet that has a diameter of 0.5 cm that can generate 75 - 100 lbs of pull force. I took physics in college so I have a basic understanding of how magnets work, but I don't have any practical knowledge. I don't know what is feasible. I found...
22. ### Electrical Build an electromagnet which can lift up to 3 kg from 26 gauge copper wire

Hey guys I want to build electromagnet which can lift up to 3 kg from 26 gauge copper wire, 12V battery (bike), so how many turns should I do and what will be length and radius of the solenoid?
23. ### How would you find the magnetic force on a piece of metal by an electromagnet?

Does the metal being attracted make a difference? How would you find the force on the metal knowing the field strength there? How would you even calculate the field strength of an electromagnet with a core? In my case, it is one of those junkyard electromagnets. thanks
24. ### Biot Savart Law with Different Magnetic Permeabilities

I would like to make a program that produces a 2D heat map showing the magnitude of the magnetic field produced by a finite length solenoid. The heat map would show the field strength along the radial and axial directions of the solenoid. I plan to divide the conductor into "infinitessimally"...
25. ### Origins of magnetic fields from permanent static magnets versus current

The videos from Veritasium explaining permanent static magnets and electromagnets were quite good I thought… But they have me a little confused with regard to the origins of magnetic fields generated by an electric current as opposed to a permanent static magnet from say iron. 1. An...
26. ### How strong should an electromagnet be to elevate a 1kg mass?

Hello Everybody, Can somebody help me to find out about Electromagnets and Electric motors? I hope that here it is possible to get an expert opinion about the next question. How strong should be electromagnet to elevate and hold f.e. 1 kg weight in the middle of a ferrous environment (f.e. cube...

Hej Guys, Did anyone see anywhere an equation to this? If nothing else then a loading time formula for solenoid would do. Thank you!
28. ### Electrical Applying current only to temporatrily demagnetize a magnet

Ladies & Gents, Instead of applying current to a non-magnet to induce magnetism, is it possible to apply current only to temporarily de-magnetize a magnet (natural or man-made)? This would seem to use up less electricity, especially since the default mode for a desktop application I'm working...
29. ### Where can I find Laminated sheets for coil core

I need to buy a 'I' shaped CRGO laminated core sheets, is there any website where I can buy online? Thanks
30. ### Electrical UHF/SHF Electromagnet Homework Solution

Homework Statement I am making a prototype and I need an electromagnet with a wavelength of the order of centimeters. The magnetic field can be 10 mT or more. The Attempt at a Solution Microwave have magnetron in it, but they don't specify the magnetic field since it's not the purpose of the...
31. ### Calculating the final velocity of a simple electric train

I am currently in grade 12, and for a physics project (a huge project, which gets assigned to you at the start of the semester and needs to be completed just before exams. You think up your project, make a proposal for it and you prove your hypothesis to be right after a presentation and lab...
32. ### Electromagnet Model: Couple Questions Answered

Couple questions concerning this design: - Would the object sit relatively still? As I assume in this design the magnet would not have to switch on and off repeatedly (as it would with traditional magnetic levitation) as there is a physical force applied to it? - I'm guessing the rubber barrier...
33. ### Generating electromagnetic fields with an electromagnet

Hello, I am working on a science project to generate electromagnetic fields. From what I understand, the simplest way to do that is to coil copper wire around an iron core. My initial goal is to create a magnetic field with a maximum strength of 500 microtesla. Can this be accomplished if I...
34. ### Launching satellites using electromagnet power

Why can't we launch satellite by using electromagnet power?
35. ### Where could one buy an electromagnet for lifting 200kg

Years ago my father had an electromagnet he used for children's science demos. It was powered by a little 9 volt battery. He would attach a rope to the magnet and another to a steel plate. He would then have the kids try to pull the magnet apart via tug-of-war. He also brought out his magnet at...
36. ### Magnetic field of an inside out electromagnet?

What if an electromagnet's core is on the outside? How would it's magnetic field look? (The wire being wrapped in coils on the inside of a tube or pipe looking metal)
37. ### Electrical Create an electromagnet stronger than a fridge magnet

Hello, I have a question. I would like to create an electromagnet that is generally stronger than a standard fridge magnet... Right now I have this set up, (please tell me if what I am doing is wrong or unpractical). I have 10 AA batteries ligned in parallel to a 3 inch iron nail. I spliced a...
38. ### Helmholtz synthesizer experiment

Hello all! Inspired by the Helmholtz synthesizer, I am experimenting with electromagnetic excitation and tuning forks. http://www.sites.hps.cam.ac.uk/whipple/explore/acoustics/hermanvonhelmholtz/helmholtzssynthesizer/ How can I determine the size and charge of an electromagnet in order to...
39. ### Induction: Electromagnet and Aluminium Ring

I need some help with this task, I am stuck. 1. Homework Statement An aluminium ring is placed on top of an elctromagnet. a. The electro magnet is connected to AC. What will happen with the aluminium ring? Motivate your answer. b. What will happen with the ring if the electromagnet is...
40. ### Magnetic field of a circular electromagnet?

I know that the poles of an electromagnet that is straight is at the ends but what if the metal core is an iron ring?
41. ### High Frequency Electromagnet Possible?

I was wanting to build a very high frequency electromagnet to test an idea and it requires something in the range of about 1-10 GHz, and I'm unable to find much information on what I'm attempting to do. I understand the impedance will be incredible, along with some other technical issues. Most...
42. ### Electromagnet -- changing flux and a ring

Homework Statement Homework EquationsThe Attempt at a Solution If an observer stands between A and B then he/she sees current flowing in clockwise direction in A .Now if current in A increases , flux linked with B also increases .From lenz law current should flow in clockwise direction (from...
43. ### How to calculate magnetic flux from voltage?

I understand that magnetic flux density is measured in Teslas or Weber’s per square meter and that voltage or emf is measured using faraday’s law of induction which is E= - N dφ/dt Where N= number parallel fields Φ = magnetic flux (Wb) E= emf (V) What I don’t understand is the time function...
44. ### Homemade electromagnet, considerations - strength

I'm making a solenoid electromagnet for gcse demonstration purposes and I'm trying to get a strong:muscle:, clear magnetic effect. I'v wrapped about 100 turns of enamel plated copper wire around a 4" bolt and also a 4" ferrite rod, and am applying 9v DC from a pp3 battery cell. In both cases...
45. ### Repulsive force of an electromagnet and a magnet

I have been researching for quite a while about this subject and I only got more confused. I want to evaluate the repulsive force between a magnet of 52 MGOe and an electromagnet. The goal is to generate a repulsive force of say 75 Newtons. So I am using a neodymium magnet N52 how can I figure...
46. ### Electromagnet Design for Separating Ferrous Material from an Ore Mixture

Good day I've been the task of designing an electromagnet to remove ferrous material from ore mixture. I've calculated the flux density require to remove the particle from underneath a burden depth of 400mm; which is 792.7177 Gauss. (Force index is: 1.5710*10^6 G^2/m) However what I've been...
47. ### How to make a short range, remote-controlled electromagnet?

I am currently working on my high school's upcoming production of Beauty and the Beast. In the musical, there is a rose which loses petals at specific moments in the script that represent the castle's inhabitants slowly becoming less human. I figured that one of the best ways to do this remotely...
48. ### How to use transformers to create an electromagnet?

I want to make a powerful electromagnet using a transformer, to start I wish to to make a weak magnet using it then work up from there to ensure I make little to not mistakes since I am inexperienced with engineering. I was planning on using a transformer I got from a power supply. I have taken...
49. ### Electromagnet and a current carrying wire

Hi, My understanding of an electromagnet is that it is a material with low susceptibility and high permeability, i.e. the magnetic field is not permanent but in the application of a current then the material gets a large magnetic field. In the application of a current the spins of the electrons...
50. ### Efficient 12V Electromagnet Design for Extended Use

Homework Statement Need to build an electromagnet. Want to build one to work on 12v 7Ah battery with a switch. Needs to be on for up to a minute. Gets pretty hot. Any ideas what components can be wired into circuit and how to control current to retain magnetic field strength but reduce the heat?