Eddy currents Definition and 71 Threads

I'm trying to model a metal detector for my internship project. The system consist of one coil energised with an oscillator to create a magnetic field. The principle of the detection is by measuring the change in the coil impedance. with biot et savart law the magnetic field create by the...

I recalled a drawing that was provided in an EM text. Without going in length, the basics is simple - in order to minimize eddy currents one divides up a planar surface area of a wide conductor into small separate sections. As is done in transformer core laminations for example. In the image a...

Hi there! Recently, I am studying this kind of power loss from the following link: https://www.electricalvolt.com/2019/08/eddy-current-loss-formula/?expand_article=1 Just to summarize an idea, Supposed that we got a material, which is penetrated by a magnetic flux. The material will generate...

A piece of metal moving West to East in a North to South fixed magnetic field slows down...but how? Yes of course eddy currents are set up in the metal and these currents generate their own magnetic field which somehow slows down the moving metal piece...but how does this actually slow the...

Quick question 1st, is there a Magnetics forum here on PF? I am working on a project that is inductive heating using two coils and some simplified current control circuitry that can drive coils 10-100kHz. I have some questions around the magnetic fields and localized eddy currents. Let me set...

Hello I would like to lift aluminum parts with the help of eddy currents. The bar magnets A are plugged on the drums B or C. The drums are rotating. What is the best arrangement of the magnets (B or C) to lift the aluminum? Does anyone know ? Thanks and greetings.

When you try to create time varying magnetic fields in solid metals, there is severe heating due to eddy currents, when you increase the frequency, just like in NDT(non destructive testing) the magnetic field is pushed away from the core to the periphery due to eddy currents opposing the field...

Explanation 1: Eddy currents induced, energy loss due to joule heating. Explanation 2: Eddy currents induced, induced magnetic dipole formed. Energy is lost as work has to be done to overcome the attractive/repulsive force due to the magnet and the induced magnetic dipole from the eddy...

I have jus thought about how maybe I could sue the magnetic field strength equation for a solenoid (that I used to find the Emf in the first place) again, to find the magnetic field strength arising from the induced current: B= μNI / L where μ is the permativity of free space N= Number of...

I know that the magnitude of the eddy currents is proportional to the magnetic field, which means it should increase as I add more magnets. However I am unsure if this approach is correct.

I'm in an intro E&M class, and I'm trying to distinguish between Motional EMF for loops of wire and conducting plates. This question might be kind of silly, but are Eddy currents pretty much the same thing as induced currents in a loop of wire? More specifically, what I am trying to ask is if...

This may sound dumb.. We know metals reflect microwave. One way to look at this is considering an eddy current formed inside the metal that cause the reflected EM Flux. When glass reflects light, does something similar happen? Can we have eddy currents (or something analogous) with light since...

My explanation: A circular coil is connected to an AC supply at a frequency of 30-50 kHz (radio frequency). Therefore, an alternate current will be running through this “primary” coil, producing an alternating magnetic field. This magnetic field periodically decreases in strength, alternating...

I know only about Laminated,Iron and wooden coil.I don't know what is Air cored coil. So according to me,it should be Wooden cored coil because less current will flow through wooden cored coil.Ans it will be maximum in Iron cored coil. Please tell,am I correct or not?I don't know the answer.

Well, then: my first real topic here on PF :angel: We will soon do a half-bridge PWM thing, if everything goes smoothly. Bit of a scary thing, actually. So far it's about gathering reference material and examples. Even the simulations are just in planning phase. But: as it seems the...

Hi, guys, I am developing a simulation in Ansys Maxwell. I set up my simulation in the "transient mode", and I would like to evaluate the eddy currents that arise in a metal Vessel. The currents rise to a flat top in 20 ms and then after 20 ms in the flat top, it decreases to zero in 20 ms. I...

I’m facing strange phenomenon in voltage multiplier operation – PCB traces are overheating. Multiplier runs at 50KHz, consumes 40V / 26A and delivers 500V / 2A. The prototype is continuously monitored by IR camera due to overheating concern. None of electronic components is heating...

I have a set of little flywheels that have a magnet to break the motion of the system. I have one aluminum and several copper ones all water jet cut roughly to size. The copper and aluminum disks I have are all the same dimensions but bought from three different sources. Yesterday I machined the...

Suppose a 10k Gauss 3in diameter sharp magnetic field is made & collapses completely thru a standing human human body somewere made by an external electromagnet.. The electromagnet is held horizontally and not vertically against body. Is this hazardous? Can it become hazardous after some...

I'm trying to use a solenoid to measure the magnetocaloric effect of dysprosium. The effect is highest at the Neel temp which is down near 180K. I have a solenoid in a cryostat to get the correct temperature. The cryostat's heat exchanger is made of a thick copper cylinder and I think it is...

Hello! I'm currently working on a project that will utilize the phenomena of eddy currents to apply a braking force to a rotating disk. Some background on this project: My team was tasked to create a physical therapy training device to train patients in wheelchair propulsion at resistances lower...

Hi, In an AC 3-phase induction motor (i.e. asynchronous motor) rotating magnetic field is produced by the stator and in this case rotor consists of simple cage having metallic bars or with coils wound around the rotor. The rotating magnetic field magnetizes the rotor and attracts it. As the...

Homework Statement In one of the most common examples of Lenz's Law a magnet is dropped inside a copper tube and due the induced emf and the eddy currents generated in the copper tube the magnet falls through it with constant velocity. The external force that the eddy currents oppose is...

Hello there guys.I am currently doing an undergraduate degree in Mechanical Engineering and in order to graduate I have to do a major project by my choosing.So i I chose а magnetic brake, using eddy currents principle.We all saw that cool videos in youtube with magnets and copper tube.So i came...

For a microscale electric generator (where the driving force is a fraction of a Newton), can losses from eddy currents be significant enough to noticeably alter the rotational velocity of the rotor? Because my understanding is that the rotation is basically taken as a constant when examining the...

Hello, I was solving a problem related to Eddie currents recently and I need some help with simulating it numerically. Basically, we have a disc-like copper pendulum entering a region of uniform magnetic flux density B (see diagram). I understand that I need to use Faraday's law: \nabla...

Hi. Superconductors can be made hover above or even below magnets. As far as I know, this can be interpreted as an extreme form of Lenz's law: Eddy currents on the surface of the superconductor create an opposing force that is able to cancel gravity since the currents aren't affected by...

This is not a specific homework problem. It is a lack of understanding in theory relating to a lab report I have to write. We (my group and I) wrapped a 40 cm PVC pipe in copper wire (very densely and for almost the entire length), applied a current to it, and dropped a permanent magnet...

Hey guys, So I'm interested in the application of an eddy current brake system as a high intensity shock absorber of some sort. The system would consist of permanent magnets concentrated on a stationary, non ferromagnetic metal. If a sudden, intense force were to act upon the non ferromagnetic...

Since the field in the title is opposing the original magnetic flux that causes the induction, how can it be reduced? I understand that a laminated magnetic core can be used. 1) Where is this magnetic laminated core placed? 2) Can it be obtained from specialized manufacturers? 3) My choice for...

i tried to fig it out by watching a lot of vid on it but no chance help me

I've got a rather simple inquiry, but I haven't been able to get a straight answer via Google searches. When evaluating the impedance of an inductor, do eddy currents represent a series resistance through, or a parallel resistance around the ideal inductor? I've read that eddy currents are...

Hi pf, Could someone please explain to me why the back emf on the primary caused by eddy currents does not result in power loss. From what I have been reading about transformers eddy currents have two effects: 1) Producing heat (P=I^2R) 2) Producing a flux which opposes the primary flux I am...

If a magnet is being moved in a conducting coil, are eddy currents produced in that coil ? And why ? I think the answer is yes bcz a changing magnetic field creates eddy currents in a conductor (whether it was a coil or not) . Correct me if i am wrong . Thanks !

I had the idea of making an hourglass timepiece employing lenz's law using a magnet and copper tube (or copper bars for visibility). Any idea how accurate my hourglass will be? I know Lenz's law is effected by temperature (not sure by how much). If I drop a small magnet drop through a small...

I've been googling around, and I can't seem to find a straight answer to this: Do eddy currents generated within an inductor core change the inductance, the impedance, or both? My reason for asking is to understand whether more or less eddy currents will change the resonant peak of the...

Hi All, I am new to this forum. Thanks for viewing my question in advance. I have a confusion about the duration of eddy current. All the formulae I found are to calculate the intensity of the current. I am implementing a switch in my experiment which will turn on/off the magnetic field inside...

Im a bit confused about one point. Can Eddy current, and induced current exist at the same time...? If a conductor is a part of a closed circuit, and there is a change in magnetic flux over time, both Eddy current and induced current would oppose that change? Let's assume a conductor that is a...

I am having difficulties writing my damped oscillations lab report. We were asked to write a short essay on eddy currents (creation,direction advantage and disadvantage) and their relationship with torsion pendulums. Also,we have to explain if the copper wheel in the torsion pendulum could be...

Hi To detect position of a metal we can use the eddy currents induced by a current carrying inductor. It is described in this link. http://www.marktec.co.jp/e/product/ndt/ect/principle.html Would this still work if the target is a magnet enclosed in a metal casing. Basically I need to detect...

A metallic disc attached to a rod swings between two opposite magnetic poles, and its oscillation dies away very quickly. I thought this happens because the eddy currents formed inside the disc are established in a direction that would cause their magnetic field to oppose the magnetic field...

Hi, I am about to sit my Physics A-level paper next week and I have a couple of questions. My first question is rather broad, but what are eddy currents? I understand they're formed in transformers and how their effect is reduced, but I don't understand exactly why they're caused. Am I right...

hi all. I understand wikipaedias explination of eddy currents but could someone please explain more fundamentaly how they work. Thanks in advance :)

How Eddy Currents Produce Attractive Electromagnetic Forces--Maglev Hello, I am working on a paper about maglev systems and am trying to describe attractive electromagnetic suspension systems, but I am having a little trouble exactly visualizing how this works, which from what I have read is...

hey, could someone tell me if it is possible to measure the angle of twist of a rigid shaft subjected to a torsional moment at one end by using eddy current testing?

How would I calculate the magnetic flux density of the magnetic field generated by eddy currents induced in a circular plate? I decided it would be reasonable to approximate this by considering the flux density of a current loop. However, it is my understanding that eddy currents are induced...

Homework Statement What equation do i use to calculate the power loss due to eddy currents? I can't find an equation anywhere online.

Homework Statement How to calculate braking force generated by eddy currents. If there is a disc of radius r with conductivity K, with a magnet located at a distance r-d from the center of the disc with a magnetic field B, what is the retarding force of the magnetic field created by the eddy...

I've noticed in demonstrations that when you've got a magnetic field going through an iron core, say coming out of the page at you, that the eddy currents circulating perpendicular to them will flow clock-wise. But if you had a wire loop and put a current through it clockwise that it would...

let's say we have a square piece of metal and we put this piece in a variable magnetic field, would it get heated? is this the idea of a current? If we have a rotating metal disk (as the case of a saw for instance), and the we put this rotating disk in a constant uniform magnetic field such...