Magnet Definition and 912 Threads

I am wondering how efficient this engine can get, I am thinking if one used a superconductive magnet that is really strong?

I wonder if it would work to cast a thick-waled bowl of bismuth and drop a magnet into it, would not that levitate the magnet? I have seen other setups but they seems more complicated.

Please excuse the lay terms that will follow. I have been doing some reading on "magnetic shielding" and have come across alloys such as MuMetal which have high permeability and so can block interaction between two magnets. My question; Is this inhibition of interaction between the two...

This is probably a very naive question, but I am trying to wrap my head around the concept of flux pinning (quantum locking). For all intents and purposes, it appears as if a superconductor suspended above a magnetic field is defying gravity. I understand that there is no work being done (as...

Homework Statement My problem is trying to understand this graph and explain why it changes the way it does Homework Equations [/B] e=change in ∅/change in time The Attempt at a Solution [/B] I know that the magnetic field increases/decreases when the magnet is on the way into the coil and...

Hi. Since there haven't been observed magnetic monopoles so far, what exactly do we mean when we talk about the north/south pole of a magnet? Is it something like "north is where the field lines exit a solid body" and "south is where they enter" or is there a more rigorous definition?

We have a permanent saturated magnet. And a coil wound around it. The current produces magnetic field in same direction as the magnet. Now we know that the energy of magnetic field is proportional to the square of the magnetic induction. E1=kB12 E2=kB22 Etotal=kB12+kB22+2kB1B2 We have an extra...

Hi guys, I recently extracted a motor from an old washing machine and came across some really interesting things when I hooked it up to a D.C. power pack. Firstly, I connected a lead to each brush and powered it will 12V D.C. and it span really fast. I cannot work out why because the startor...

http://lookpic.com/O/i2/73/DYktKEGg.jpeg Hello Dear Friends We produce Lifting Electromagnet for Steel Scrap charging of Induction furnace, bottom plate of electromagnet is made of Stainless steel . my question : Can We use AL OR SILVER Spray for Spraying bottom plate that Radiation heat...

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...

Hello! I'm looking for some help regarding magnetism and how it might work (or be fictionalized) in regards to a "magic" compass. I have two questions. Please excuse my complete scientific ignorance :) In my story, our young hero has a compass. The compass needle just spins in endless...

What happens if I have a permanent magnet outside an ideal solenoid? Does the permanent magnet rotate until the system reaches an energy minimum in its magnetic fields? Or does the permanent magnet fail to rotate because the magnetic field of the solenoid does not reach the magnet? Wouldn't...

I want to know how does distance affect the magnetic field of a permanent magnet. I have read about the inverse square law and how it could apply to magnetic fields over growing distances, but doing so, I read about monopoles, which is a new concept to me. So, for the time being, I would like a...

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...

There are 2 primary flux paths in a permanent magnet brushless DC motor. One from the north face of a magnet to the stator through the coils/windings then into the south pole of the adjacent magnet. The other flux path would be from the backside of the magnets through the rotor metal they are...

Let's say I have a disk magnet that is a centimeter thick and 1 meter in diameter. Now let's apply an external field confined to a cylinder of arbitrary position, angle, and length. Let's say it has a diameter of << 1 meter, so very, very narrow. Let's presume that the external field lines are...

Hey I am a layperson, and have very little understanding of physics. I'm trying to understand the relation between a magnetic field and air and how they are similar or dissimilar in terms of disturbance in them. Let me lay out the context from which I came to think about the question...

Hi. These things can be used to magnetize/demagnetize tools, e.g. screwdrivers: How do they work? I'm particularly interested in the demagnetizer part. How do the field lines look like? And why is there this stair-like structure in the upper hole?

Hi to all. I am simulating a "core less axial flux PMG". This PMG has significant cogging torque. I don't know where this torque comes from because this is a core less generator therefor there is no slot in stator ( no reluctance variation).

Hello PF! I am about to conduct a physics experiment to write my high school level paper on. I initially was going to investigate the Gaussian Gun, but my physics teacher has said that I need to have real life, practical applications of the model, and to also have a variable I can change and...

I was curious to the effects of a strong electromagnetic field applied to an object at distance. The field must be able to quickly activate and deactivate in order to account for the distance traveled towards the object as to eliminate the force applied to the source of the field by the object...

Hi everyone! My knowledge of physics is very very basic, so I just found this great forum and I think it would be great to have a feedback from people who know. I am in development of a project that involves a laptop sleeve and some magnets. I've already done my research and found that they...

I'm talking about how like the atoms expand and the electrons get farther away from the nucleus. This might be a stupid question but how does that make it less magnetic? Like what do the electrons being farther away have to do with how strong the magnet is?

Hi Folks: This is my first post, I hope that I observing the proper etiquette. If I have a magnet with a known pull strength is there a way for me to determine the affect of 1/4 inch plywood on the magnets pull strength when the plywood is placed between the magnet and the surface metal? Thank...

I'm currently struggling with the Moving Conductor and Magnet Problem. https://en.wikipedia.org/wiki/Moving_magnet_and_conductor_problem Look at this section: https://en.wikipedia.org/wiki/Moving_magnet_and_conductor_problem#Transformation_of_fields.2C_assuming_Galilean_transformations What is...

< Mentor Note -- thread moved from New Member Introduction Forum > Hello, this is actually my first post on Physics Forums (I just joined) The question above is the one that I thought that would grab the most attention. I actually have 3 questions concerning magnets... I require a special...

when a magnet attracts the north end of a compass, what does that mean?

Hi, I have a question regarding electricity. Suppose I have a conducting wire secured to a table so it's completely stationary. Suppose I attach a resister of some small amount of resistance, perhaps a light bulb.Then I take a magnet and slowly move the magnet near the conductor so that a...

Why is it that a static electric field will exert a force on a stationary charged particle but a magnetic field from a permanent magnet will not? I am somewhat confused by this because the magnetic field in a permanent magnet is the result of spin charge polarisation which must generate closed...

Can a Neodymium magnet get back it's magnetic properties after being demangnetized? Say that there is a Neodymium magnet(Nd-Fe-B) that has been demagnetized(turned paramagnetic) at a temperature higher than its curie temperature. If I extract the demagnetized Neodymium(Nd) from the...

Hi I would ask someone that is pratical with Simulink in particular of Simscape about a problem which involve my simulation in Matlab-Simulink of a permanent magnet synchronous machine that is connected, by a rectifier, to a DC current source. all the blocks of the simuation are included into...

Hello! I'm wondering if there's a general dependency/connection/correlation/function for changes in distance between an electromagnet (coil with iron core) and a magnet (Samarium Cobalt). Here's a picture to explain what I mean: If I move the coil closer to the magnet (smaller x) the force...

Hello there, can anyone tell me what is a permanent magnet motor drive train and what is the working principle of permanent magnet motor drive train ? i have searched google but i couldn't find anything useful

Homework Statement Homework Equations I am not really good at this topic, but I think you would need both the right hand rules (one that involves finding direction of current via magnetic field as well as the one for finding magnetic force) The Attempt at a Solution So I drew out magnetic...

I am trying estimate the approximate value in gauss of the magnetic field of a magnet I have based on its pull force, and I am wondering if anyone can comment on the validity of my method. I have tested the pull force of my magnet by weighing the heaviest object it can hold. I have also found...

It's a random thought I had. Let's say you have a single perfect permanent magnet. There is just one magnetic domain, and the magnet is cut so that its magnetic moment is along a single crystal axis. For example, we can imagine a cube shaped magnet, with the magnetic moment pointing straight...

Every magnetic dipole has a magnetic moment associated to it. Magnetic moment of electromagnets could be found by ##M = iA##. But for permanant magnets how it is measured? If we use this formula it implies that there must be some internal current flowing in permanant magnet. Is it true? What...

Hi everyone, I have lots of (potentially dumb) questions about this "project" I'm working on. It's a voice coil actuator, but with things a bit reversed. Here's how a regular voice-coil actuator is constructed: The rod that is inside the coil is a magnet and the outer cylinder continues the...

According to theory, the magnetic field of a permanent magnet is due to the combined effects of billions of microscopic magnetic moments. I'm trying to use the Biot -Savart Law for billions of microscopic currents to approximate a the field of a permanent magnet. How should these currents (or...

According to a magnet manufacturing site, the force required to move a magnet that is attracted to a metal plate laterally away from underneath a magnet is minimal relative to the force required to move it away from the magnet directly away in the opposite direction of pulling force. Assuming...

I came across this problem: Explain how you would determine which was the north pole of a bar magnet, without using any other magnet. I was thinking of using a solenoid, and dropping the magnet in. Then you can determine whether it was a north or south pole by whether the current flows...

I have an issue in determining what side of a magnet is north and south. The only data I have is that garnered from a lab on induction, and I have taken note of the all the polarities of the circuits. The magnet was not labeled, but we noted that one end was "flat" and the other was "jagged"...

Hello, I'm trying to find an equation which describes B(z) inside of a permanent ring magnet that is axially magnetized. Also, depending on if the equation holds true, if the ring magnet will behave as a magnetic mirror. Below is an equation which describes the axial field of such a magnet...

I have noticed there are a few designs for permanent magnet brushed DC motor, but I can't seem to find the benefits and downsides of either one. The first one (first attachment) uses three electromagnets placed on a triangular rotor. There are two arc permanent magnets on the outside. In this...

Homework Statement I[/B] I am trying to find an equation that relates the velocity of 3 magnet when it falls down a copper tube to my measurement. The length of the copper tube is L=0.24m, The total mass of the 3 magnet is m = 4.98x10-3kg magnetic flux density B = 428mT, the thickness of the...

Lets us say that two magnets of unequal strength have one pole each lined up facing the other magnets pole. For convention magnet 1 is an electromagnet with an air core and a 200 gauss field strength. Magnet 2 is a neodymium permanet magnet rated at 20,000 gauss. Assume the "north pole of magnet...

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...

Can a magnetic Halbach array have less than three (i.e. two) magnets in the array? I can't seem to figure this out quickly with google. TIA!

Probably a stupid question, but I do not get it... Here you can see an experiment demonstrating the Gaussian gun: Here I understand how momentum is conserved, i.e. the smaller mass of the ejected ball times its high speed is equal the bigger total mass of the recoiling masses times its...

Hello all, new here but plan to stick around for a while. I am currently trying to make a sensor that can detect if a material below it is paramagnetic. I believe paramagnetic is the proper term, but it needs to detect if the force exerted by permanent magnet is above a certain threshold. The...