Electromagnet Definition and 371 Threads

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. PJP

    Electrical Heating Problem with DIY A/C Electromagnet

    Hello every one I’m a newbie to electrical stuff (I do have basic knowledge) so please be patient with me, please help me! :frown: So, coming to the details of my diy project I’m trying to vibrate a metal string with an electromagnet. so, after an ample amount of research I’ve made the...
  2. VSayantan

    Speed of a Magnet Falling through a Conducting Wire

    Homework Statement A small but very powerful bar magnet falls from rest under gravity through the center of a horizontal ring of conducting wire, as shown in the figure below (on the left). The speed-versus-time graph, in arbitrary units, of the magnet will correspond most closely to which of...
  3. S

    Electrical DIY Electromagnet: How to Make or Buy One for Lifting Up to 178 Pounds

    I want to make an electromagnet that can carry me or buy one. I weigh 128 pounds (58kg) and I found an electromagnet with a pull force of 178 pounds (80kg). https://www.amazon.com/dp/B01EWHSF3K/?tag=pfamazon01-20 Can I attach any 12v source to power it or does it need a specific amperage. And...
  4. B

    Electromagnet polarity switching....

    I regret I know nothing about subject but wonder if anyone could advise where I could obtain a device (including magnets) which will change the polarity of two electro magnets from once per second to hundreds of times per second?
  5. S

    Using an electromagnet as a magnetometer

    I am new to this site and I am not a physics / engineering professional. Please excuse me if I only have a layman's understanding. I have been trying to make a device to sense a 2 foot long by 2 inch diameter rod at an 8 foot distance (all steel, all ferrious). to be detected. I have tried home...
  6. C

    Can diamagnetism be created electrically

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  7. peroAlex

    Electromagnet with two cardboard pieces

    Hello! Recently I was going through some old exams and upon encountering this problem (which seemed pretty easy) I got stuck. Exams at my university are composed of individual tasks, each having three subquestions with four plausible answers respectively. Solution sheet gives results only, so...
  8. M

    Electromagnet force on object at some distance

    I've searched high and low and come up with a lot of "maybes" and "could be's" and "try this" to a problem which I feel should have at least a few example calculations floating around the internet. The questions is trivial but it seems like the solution is fairly complicated. I'm not looking for...
  9. E

    The Peculiar Behavior of a large electromagnetic coil

    I have these two very large (ferrous core) coils, They are basically identical, each 200mm long and have a diameter of 100mm. The core is medium grade steel One coil is receiving an input of 8V(peak-to-peak) @ 4 MHz from the function generator. The second coil is placed 1m away, and is...
  10. C

    Need help doing force calculations with magnetism (between magnets)

    I am trying to calculate the forces (in Newtons) between a permanent magnet, and an electromagnet. All I can find is interactions between permanent magnets, electromagnets, but never both and it is getting really confusing for me to do the calculations. So basically, if I have a permanent...
  11. S

    Electromagnet attracting permas

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  12. C

    Bar magnet wrapped in electromagnetic coil

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  13. r_prieto5

    How Do You Calculate the Force of a Solenoid to Lock a Neodymium Triangle?

    Hello everyone, So for a personal project I want to calculate the force necessary for a solenoid (electromagnetic coil) to keep a permanent magnet triangle locked diagonally up and down at the same time so that it does not move in any direction. I need to know the values for coil thickness...
  14. K

    Could Electromagnetic Levitation Create a Feasible Hoverboard Solution?

    Hi, My name is Kendall. After seeing the Back to the Future again, I have been once again fascinated by the hoverboards, as I'm sure many others are also guilty of. A couple hours of research into magnetism later, and I'm still stuck. I have little to no experience with magnetism, but I figure...
  15. J

    Electromagnet for an Arduino board?

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  16. A

    What is the benefit of using an electromagnet in a generator

    Mentor note: Post moved from Educators and Teaching section Hi I would appreciate some clarity regarding using electromagnets as generators? Why are they used instead of permanent magnets specifically given that electrical power is needed? What is the difference between the power in and power...
  17. T

    How to Design a Donut Electromagnet

    I have an electromagnet device that I am designing and need a bit of help from some of the brilliant people on this site. Here's the problem: I have a disk attached to the end of a shaft and the shaft/disk assembly can move radially (via a spring loaded mechanism). This shaft/disk fits...
  18. 1

    Help designing/finding a vendor for this magnetic field

    I need help find a electromagnet suitable for this http://imgur.com/a/vkm4T Each electromagnet (the 3 in the center) needs a repelling force of about 20 to 40lbf. I stupidly bought these from amazon http://a.co/aSftIat. Its a holding electromagnet so the N and S poles are essentially on the same...
  19. L

    How Can I Make a Small Electromagnet as Powerful as Possible?

    Hello, i need a small electro magnet with it's dimension not bigger than 8 millimetre (0,31 inch) in diameter with a length under 10 millimetre (0,39 inch). I want it to be as powerful as possible, where do i find such magnets? And how should i make my own? How powerful is it possible to make...
  20. M

    Junkyard sized Large electromagnet

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  21. S

    Large electromagnet with unusual requirements

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  22. N

    Can heat damage the magnetic properties of an electromagnet?

    Electromagnets heat up quickly...shouldn't heat destroy its magnetic properties?
  23. P

    EI Core electromagnet questions

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  24. V

    Building an electromagnet, would appreciate advice

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  25. A

    Flux Pinning in a type 2 SC Using an AC Electromagnet

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  26. Z

    How to Design and set up a strong electromagnet?

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  27. KaleLetendre

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  28. J

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  29. C

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  30. S

    Electromagnet magnetic field strength

    Homework Statement Homework Equations ##\oint_{C} Bd\ell = \mu I_{enc}, B_{normal}## continuous across boundary, ##H_{parallel}## continuous across boundary The Attempt at a Solution $$\oint_{C} Bd\ell = \mu I_{enc} \rightarrow B = \frac{\mu NI}{2\pi r}$$ Any help much appreciated. How...
  31. Chris Fuccillo

    Force on a permanent magnet from an electromagnet

    Hi again and thank you again for the help If I have two magnetic fields, one permanent ring magnet B2 free floating on a fixed electromagnetic coil B1 and the field are perpendicular 90 deg to each other will the free floating permanent ring magnet feel a strong magnetic torque and rotate...
  32. Metals

    In an Alternator, is the armature an electromagnet?

    Hey, I'm lightly studying 'Generating' as a topic in my Physics curriculum. I have just been introduced to an AC Generator, an Alternator, and I have a simple question: Is the armature in an alternator an electromagnet? From my understanding, there is a U-Shaped length of wire(s) which...
  33. jim hardy

    This fellow wants to make an electromagnet....

    Following is a conversation that was started by a fellow tinkering with a MOT which can be very dangerous but to his credit he DID remove the deadly high voltage winding(at least he said he did). It belongs in a thread so I'm moving it here ------------------------------------------...
  34. A

    I need to create a .7+ Tesla electromagnetic solenoid

    I am trying to create a solenoid with a high flux density, but I need the specifications (wire gauge, current applied, etc). The diameter of the core would be preferable around 15mm. The length can be pretty much anything reasonable. I need this for a project that requires a strong repulsive...
  35. M

    Using Electromagnet to Detect Steel Door

    Hi guys, I'm using an electromagnet to detect the presence of a steel door through analog pins on an Arduino. This works great if the magnet itself isn't under power, but once I'm running 12 volts through it, the sensitivity of the readings fall apart. I'm using a resistor based voltage divider...
  36. S

    Electromagnet which produces varying magnetic flux

    I want to make an electromagnet but it should Produce magnetic flux which changes with time. What material wire would be the best to make make windings?
  37. A

    Testing the strength of an electromagnet....

    For our physics class we have to design an experiment investigating the factors affecting an electromagnet's field strength. I have decided to investigate the number of coils in the wire. My only problem is, I'm not sure how to measure the field strength. Our teacher gave us two things which we...
  38. M

    Does diameter of air coil in electromagnet affect strength?

    The title is explanatory. I know that an iron core yields a stronger electromagnet. What if you have an electromagnet with an extremely tiny air coil relative to its volume? Does the small air coil diameter effect the electromagnet?
  39. S

    Uncovering the Strength of SEM's Electromagnetic Lenses

    Does anybody happen to know the strength of the electroMAGNETic lenses of a scanning electron microscope? I was thinking of using solenoid coils, which would be enough if I am willing to increase the focal distance, but the lenses on SEM's seem far larger.
  40. A

    Maximizing Repulsive Force: Formulas for Designing Electromagnets?

    I want to design electromagnet for my project. I want to know which formulas are used while designing electromagnets and methodology if we know repulsive force we require at a distance of 25mm from one end of electromagnet.
  41. Raymond Hart

    Is an Electromagnet Sign a Viable Solution for Preventing Sign Vandalism?

    I am making a sign out at my farm. I am making everything myself and have come up with an idea on getting the letters to stick to the front of the sign with magnets. I just have plastic letters with magnets glued to the back and they just stick on the front of the sign that has a galvanized...
  42. R

    Conductive ring levitated by electromagnet

    I am an eleventh grade student currently in AP Physics C. My teacher did a demonstration with an electromagnet where he drew AC current from the wall to shoot a conductive ring. I was wondering where i could find the blueprint for such a device, or perhaps receive some guidance on how many coils...
  43. B

    Can Electromagnets Achieve High Holding Force with 30cm Separation?

    Hi, I am investigating the possibility of using 2 oppositely polarised electromagnetics to locate 2 moving bodies into the correct position as they move towards each other and would appreciate some thoughts on the feasibility of the solution and ways it might be improved. I am proposing using...
  44. J

    [Uni Physics 2] Inductance Problem

    Homework Statement Two identical long wires of radius a = 2.90 mm are parallel and carry identical currents of i = 5.00 A in opposite directions. Their center-to-center separation is W = 17.0 cm. Neglect the flux within the wires but consider the flux in the region between the wires. What is...
  45. R

    Calculating Inductance of a Solenoid with Multiple Isolated Loops

    I found this formula to approximate the inductance of a coil of wire. But what if a solenoid were composed of N separate loops, where each loop of the solenoid is connected to its own battery? That is, what if the solenoid had the same number of loops and the same geometry, except that each loop...
  46. A

    Force on Magnet from Electromagnet

    Hello Everyone: Take a look at the following diagram Assuming the coil build above. How would you determine the force pushing-pulling the Neodymium Magnet in the center of the plastic pipe. I know the number of turns, length, amperage are in effect.
  47. E

    Moving an iron sphere along a path with an electromagnet

    Hello, So I am working on a project that requires the movement of iron nanoparticles (let's assume 25nm in diameter, and let's assume the sphere is uniform and pure iron) through a (non-magnetic) gel using an externally applied magnetic field. Let's assume the total distance I want to move the...
  48. MironeDagains

    Very basic electromagnet vs permanent magnet question

    When you switch on an electromagnet (who's north pole is pointing to the left), is it the same thing as if you had pushed a permanent magnet to the left? Or to the right? I believe it's to the left. But apparently my textbook thinks it's to the right. Who's correct? Why I'm asking:I've attached...
  49. D

    How Can I Control an Electromagnet with a MOSFET for a 9V, 6A Project?

    I'm working on a project where i need to control an electromagnet but I'm not sure how to do it. I tried using a npn but the current passing through the magnet is just to small, should I use a mosfet instead. The specifications for my project say that they will provide us with 9 volts and a...
  50. Murdock

    Calculating field strength of an electromagnet

    I would like to build an electromagnet to accelerate electrons into a circle (a precursor to a mass spectrometer). I would like to calculate the field strength, but I don't know how because I would like to wind it out of aluminum strap salvaged from a welder, and I can only find formulas for...
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