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. C

    How Do You Calculate Resistor Values for a MOSFET in an Electromagnet Circuit?

    Hey, so currently I am trying to achieve a working electromagnet that will be powered by an AVR microcontroller and will be turned on and of when metal is sensed. Currently I have LED reflecting and sensing the block which passing through the photo diode and tells the AVR when to turn on the...
  2. Blackhawk4560

    Calculating Vectors (in Joules) of an electromagnet

    Good afternoon, Question: Say I have an electromagnet at a 45 degree incline from an electron beam. This electromagnet is exerting 0.75 Tesla on the beam. How can I calculate the vector that the electromagnet will exert on a particle? Note, this is for my own curiosity, not for any homework...
  3. S

    How to calculate force from an electromagnet?

    Just what the title says, how do I calculate the force, in Newtons, that an electromagnet would have on an object?
  4. Dare Diamond

    Maximum Voltage To Apply To An Air core Electromagnet

    Hello everyone. I am glad I came across this science oriented Forum site. I actually get there from Google and what I am deeply curious to know about is the amount of Maximum Voltage my 3.5kg Air Core Electromagnet can bear. The Core of the Solenoid is 120mm in height and 13inches in...
  5. 4REEL

    Basic (I think) question on electromagnet combos

    Hello, I'm brand new to this forum. I'm an artist and musician and have just recently started delving into inventing, my scientific knowledge is very limited. I've made a simple electromagnet but I want to get the strongest pull between the magnet and another small surface. I want strong pull...
  6. C

    Very Large Diameter Electromagnet (solenoid)

    I am toying with an idea and not sure if it's feasible. Here is the setup: There is a 6' diameter steel pipe that is 30' long standing up vertically. Inside, among other stuff, are ~20 small 'trolleys' on tracks that run from top to bottom, spread out evenly among the cross sectional area of...
  7. M

    Making Steel Wheels Magnetic for Model Train Track

    I have a project I'm working on where I need to have a model train be able to have an electromagnet hold its wheels to the track -- so that it can go "upsides down" and resist derailment. I'm making the wheels and the track -- so all options are on the table. If I used a steel track (say...
  8. A

    I need to build an electromagnet to provide 10mN eddy current brake

    Hi I am building a motor tester, for that I need to build a variable load. For which I was planning to use eddy current brake with electromagnet. Please help me to build a electro magnet which can provide more than 10mNm load to a DC motor with rotating disc of 75mm in a RPM of 6500. I tried...
  9. psvtrajan

    Electromagnetic Engine: Can It Power an Engine?

    Is there any engine which works using electromagnet?
  10. R

    How can i calculate the resistance of this electromagnet?

    I would like to find a ballpark estimate of the resistance caused by an electromagnet such as this: http://www.ebay.com/itm/12V-DC-22-LB-10kg-Electric-Lifting-Magnet-Electromagnet-Solenoid-Lift-Holding-/360519627296?pt=LH_DefaultDomain_0&hash=item53f0a4f220
  11. R

    Force of an electromagnet question

    Homework Statement A solenoid which is 0 meters away from a ferrous piece of metal exerts how much force on it? there is 0.42 amps, and 1000 turns in the coil. the cross-sectional area is 2.8502e-4 meters^2 Homework Equations Force = ((N x I)^2 x k x A) / (2 x g^2) N = the number of turns in...
  12. R

    Need to build a Large Lift Electromagnet

    Hi Everyone, not sure why it is so difficult to find any info on how to build a simple electromagnet with diagrams or plans... but it is! I need to lift sheet plate... thousand poinds or more... something like a 2 car battery design electromagnet for lifting... Please, Please, don't tell me I...
  13. Jackson Lee

    Relationship between static electric field and electromagnet

    Hey,guys. I was confused by the building process of static electric field.There must exist some process building static electric field in the space. But what create it? How much time is needed? Is there any relationship with electromagnetic waves? Any one know this
  14. R

    Will a 9V electromagnet work with a battery of a lesser voltage

    Will 12v electromagnet work with a 9v battery?
  15. J

    How do I calculate the repelling Force of an Electromagnet?

    Hello everyone, I am working on a project and I am trying to figure out the formula to use. My goal is to calculate the amount of current needed to create an electromagnet with a strong enough field strength to repel a force of 2000 Newtons. thank you
  16. R

    Can I make an electromagnet attract to either pole of a mag?

    Can an electromagnet like this one be manipulate to attract either pole of a permanent magnet by running the current in either direction? http://www.ebay.com/itm/Metal-11LB-5kg-0-5A-Electric-Lifting-Magnet-Holding-Electromagnet-9V-DC-50N-/161550273936?pt=LH_DefaultDomain_0&hash=item259d258d90
  17. Shahryar

    Help to make a solenoid/Electromagnet.

    I need to make an electromagnet with maximum 20mm dia including winding. I have an iron core of 10mm dia and 20mm length. I can't decide - which wire to choose, - what no. of turns should i provide - how much current should i pass through the wire. - what should be the voltage. Any help and...
  18. M

    Why is it important to use insulated wires in an electromagnet core?

    Hello everyone, I read somewhere that it is preferable to use insulated iron wires instead of a single iron core inside an electromagnet. Anybody has an idea on why is that and what difference does it make to use each? Thanks in advance.
  19. EddieP

    Magnetic powder in a solenoid - how would it react?

    Suppose I have a plastic tube about 70% full with magnetic powder, with a copper coil solenoid around the cylinder. By "magnetic powder" I mean each particle is actually a tiny permanent magnet with its own magnetic field. - like you can see in this video When there is no externally applied...
  20. S

    How can I safely assemble a pulsed DC electromagnet for eddy current levitation?

    I need advice on assembling a pulsed dc electromagnet. I'd like to experiment with eddy current levitation. I've seen educational videos where a pulsed DC electromagnet will generate eddy currents in a plate of aluminum, which creates is own magnetic field, and causes the plate to levitate due...
  21. R

    MRI Electromagnet Interference in a Figure-8 cable

    The prevailing wisdom is that coiling excess signal cable under an MRI magnet for storage in a figure-8 configuration will reduce or eliminate induced noise onto the cable from the pulsing fields from gradient coils. I am starting to doubt this, however. A quick diagram of a figure-8 looped...
  22. T

    Calculations of a half loop electromagnet

    Homework Statement This is a past exam question which I just for the life of me can't figure out. http://tinypic.com/r/2eq6ryo/8Homework Equations My guess is that the energy of the magnetisation is equal to the gravitational energy Relevant Equations: Ems = Mass * g * δ Where Mass = ρ *...
  23. supak111

    Electromagnet, current vs voltage, same?

    Would these two electromagnets be the same strength? I can NOT change turns, I can only change wire gauge and voltage. What are the advantages if any of either one? Electromagnet with at: 10vDC at 10amp - VS - 100vDC at 1amp [Mentor's Note: Thread Title Edited]
  24. hackhard

    Electromagnet to attract small iron pieces

    i want to build an electromagnet which can attract small iron pieces(2-3 mm long) at a distance of 10 cm from the magnet.I am using 24 awg. magnet wire.Please help .answer these questions - 1) How long magnet wire (24 awg) do i need? 2)How much current 3) what shud be least radius of solenoid 4)...
  25. EddieP

    Repelling a very weak permanent magnet with an electromagnet

    I have a question about magnetic repulsion. Suppose I have a permanent magnet (axially magnetized) placed on top of the iron core of an electromagnet. I want to switch on the elctromagnet to repel the permanent magnet. (Please assume the permanent magnet is contained in some kind of tube that...
  26. Y

    Can I Use an Electromagnet to Repel Aluminum?

    Homework Statement I have made an electromagnet using the primary core of a microwave oven transformer and a 1.5 D cell battery. I would like to use the electromagnet to repel an aluminum bar (1 in. dia., 3 in. in length, and 1/4 in. thick; it is shown in the picture) For some reason, the...
  27. T

    Why is a metallic ball attracted to an electromagnet?

    I always heard that magnetic forces don't do work, and that they act perpendicularly to the direction of movement.
  28. EddieP

    Calculating magnetic field for a micro solenoid

    I am trying to calculate the magnetic field (in tesla/gauss) of an iron core electromagnet that is very small and has very few windings. For example 12 windings over 0.003 meters. I know this is not going to produce a very strong field, but I would like to pulse a strong current through the coil...
  29. T

    : Is it possible to make an electromagnet w 2 like ends?

    HELP! Is it possible to create an electromagnet with one continuous wire with 2 like poles (i.e. both ends either north or south)?. Visualising it with the right hand screw rule for current carrying coils, it will be like the picture below, but one end of the coil will be as shown, while the...
  30. R

    Powering electromagnets with bicycle power

    Would it be possible to operate an electromagnet using the power produced by pedaling a bicycle? The electromagnet would need to be strong enough to lift up the training wheels of a bicycle.
  31. Keystone

    Bending Light? – Questions & Answers

    Hi , so , i am not asking this question for invisibility or anything like that, but i do have a few questions. First off, i know that photons have no charge, but is there any way that electro magnetic pulses can effect their path when the copper coils that make the electro magnet are at very...
  32. R

    What is magnetic field intensity H?

    Hi all, My question is, in electromagnetism, magnetic field intensity H is equivalent to electric field intensity E , right?? Now, definition of E says that E is the force experienced by an unit positive charge in an electric field created by a source charge. So what is the definition for...
  33. 1rel

    Electromagnet control circuit

    Recently, I was trying to control the strength of an electromagnet with PWM over a MOSFET or IGBT with an Arduino/microcontroller. It worked but I burnt multiple MOSFETs/IGBTs while testing it, after certain time... so something must have gone wrong... I'd like to build a simple circuit, to...
  34. S

    Help with B field for a homemade electromagnet

    Homework Statement I'm doing a physics demo, and I've made basic electromagnet using some copper wire, a 6 volt battery, and a carbon steel screw, and I need help checking my calculations because I think the magnetic field for my magnet is too large. I've double checked everything and can't...
  35. O

    Free 3D software for calculating force of electromagnet?

    Hello! I need to build an electromagnet for my DIY project. But I have a problem with choosing right configuration. But I have not found any open-source or student-license software for this goal... It would be great if someone could post some links to that kind of software.
  36. A

    Electromagnet with high remanence

    I am in search of an electromagnet which has high magnetic remanence (or retentivity) even when the current through the electromagnet is zero. Can someone provide information about such a material?
  37. D

    Permanent magnets vs Electromagnet

    I've been trying to figure this out for hours.. been studying for my final exam. Can somebody please help me? Are there any differences between the magnetic field around a permanent bar magnet and electromagnet? Any similarities?
  38. E

    AC electromagnet and aluminium levitation

    Hi all, I'm new to this forum as a member, but have come across some of the topics here via google in the past. I'm trying to build an AC electromagnet levitation device, to levitate a small piece of aluminium. My knowledge in physics is limited to popular science and interest, but I am pretty...
  39. PhiowPhi

    Electromagnet & Magnetic field range in milliseconds?

    How is it possible to build an electromagnet(magnetic field of 1 - 5 Tesla) that could create the magnetic field in milliseconds or less? Electromagnet designs that I found would have high resistance & inductance, creating a field in 2 - 5 seconds. Although, they would consume 15 - 20kW of...
  40. H

    Quickly switching electromagnet polarity. Inductance issues?

    Hello all, There are a million threads and a million Google hits out there on the topic of switching the polarity of an electromagnet. Very simple stuff. But none seem to touch on the issue of inductance. I am building a small linear actuator that will be a coil wrapped around a thin plastic...
  41. akashverma

    Explaining the Repulsion of an Electromagnet on Metals

    Can it be possible that an electromagnet would repel a iron block?? if yes then please explain.
  42. D

    Self-inductance electromagnet circuit

    Homework Statement The wire in an electromagnet has the resistance 125 ohms and a parallel resistor has the resistance 4 kiloohms. The magnet is kept magnetized by a DC voltage 40V. What is the voltage over the electromagnet soon after switch K is opened? Also comment on the polarity of the...
  43. F

    Build an Electromagnet Project to Lift Objects

    Hi Everyone, I hope this is ok to post in this section this is my first time on here. I recently was watching a show on maglev trains (I know this is not new technology but I found it really interesting). I love to tinker with little projects in my shop and was wanting to build a gadget to lift...
  44. C

    Please help designing a specific electromagnet

    [/ATTACH][/ATTACH]I need some help designing my electromagnet because I am a bit lost with it I need to work out the gauge of the wire to be used, the resistance of the wire needs to match the battery's internal resistance for max power transfer I need to work out the most amount of turns...
  45. collinsmark

    During childhood, did you ever construct an electromagnet?

    In my childhood, I played with various electrical and mechanical things -- sometimes taking them apart and putting them back together. Sometimes building them from scratch. Have you ever made a simple circuit such as an electromagnet as a child? It could be as simple as wrapping some insulated...
  46. Undacuva

    How to wire a STRONG electromagnet

    Hi everyone, I have a 12mm long hard ferrite core that I want to use as an electromagnet. I have wound it with 0.8mm copper as tightly as I can by hand, in a single layer, but the field is not strong enough. I have placed another coil over that first coil, and then a third coil, each in...
  47. T

    Speed of light demo using pulsed electromagnet

    Greetings PF. I've got an idea for a demonstration of the speed of light utilizing a pulsed electromagnetic coil and ferrofluid. I'm concerned with the feasibility of this project as it may push the limits of semiconductor technology. I would appreciate any insight on the difficulties of...
  48. M

    AC Electromagnet Core Material

    I'm attempting to build an alternating current electromagnetic coil and want to maximize its potential field. My initial query was to find the very best core material for the electromagnet. I found an older post (2005) on the subject and saw some very interesting answers there. Being new here...
  49. D

    Making an Electromagnet to carry 1kg

    Homework Statement To create an electromagnet capable of carrying 1kg without it being too dangerous i.e utilizing a car battery. Homework Equations Strength of electromagnet is dependent on number of turns and current. V=IR I=V/R The Attempt at a Solution Used hot galvanized (I...
  50. E

    Usefulness of lower-impedance, faster-response electromagnet

    Given an electromagnet which has a drastically lower impedance than other, comparable electromagnets (same diameter, same gauge wire, same field strength), and, consequently, a much faster response time, what uses do you see this being good for? I'm looking to put together a patent...
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