Permanent magnet Definition and 109 Threads

Hello all, I'm a mechanical engineer who recently recently became interested in linear motors and generators (random, i know). I've narrowed my interest to tubular linear permanent magnet motors (servo types) such as the ones made by these people...

OK... so my understanding is that a DC generator under no load generates high voltages without any current, but does the same hold true for an AC alternator? What happens with current when the RPMs of the alternator exceed what is necessary for the current requirements?

Hello all, I am a newbie here but have a question that I was hoping someone could answer. Would a permanent magnet give off a single frequency or would it give off a spectrum of frequencies, like an incadescent light bulb can give off a spectrum of frequencies? I can measure the intensity...

If you were to levitate a superconductor using a permanent magnet due to the effects of the Messiner Effect, and you were then to lift the permanent magnet with your own hands, would you be lifting the mass of the permanent magnet, the mass of the permanent magnet + the mass of the...

Im looking to do some projects with permanent magnets. I don't have access to a gaussmeter and I'm wondering if there are any sites that have representations, descriptions or formulas for the field strengths of ferrite or neodymium magnets. Also i need to learn about how magnetic fields...

Homework Statement Homework Equations The Attempt at a Solution What is the expression for the magnetic field of a magnet? Biot Soviet law cannot be used since there is no current. What should I do? I get stuck at the final step shown below.

New here, hello all. My question is more about the field magnet in a running DC motor. First of all, does the current required to maintain a magnetic field change with the load on the motor? And if so, where would this "extra energy" come from in a permanent magnet DC motor?

My Question is same as the title of this thread.. and Secondly.. what is the difference between electromagnet and magnet??

Hi, when a perment magnet machine is designed for a particular power but is operated at a much lower power, is it inefficient as with induction machines? Thanks

Suppose a permanent bar-magnet is placed inside a toroid/torus and the toroid is then completed and power applied. How will the magnet move? Will it move?

Hey! I am trying to find a permanent AlNiCo magnet with a magnetic moment of 0.06Am^2. However, most magnet data sheets do not list the magnetic moment of their magnet. Often they list the Magnetic field in Tesla or the moment in Vs*cm. How can I convert this data into the magnetic moment...

I'd like to make a strong (~0.5 T) solenoidal field with a permanent magnet for a Faraday rotation experiment. If I take an ordinary cylindrical permanent magnet (with an axial field) and drill a hole down the center of it. What's the field deep inside at the center of the hole? Some of the flux...

I was wondering what it would be like if you had a permanent magnet inside the core of a material capable of obtaining the superconducting state. And you cooled it down so that it becomes a superconductor. Assuming it didn't explode; would it just condense the magnetic field into some...

Is it possible to estimate the magnetic field strength of a permanent magnet from the heaviest weight that the magnet can lift? The heaviest weight that can be lifted can be found by trial and error. Any comments or suggestions appreciated. inkpot

I've recently attempted to calculate the force of repulsion between two neodymium magnets. The problems arise fairly early when I don't know how. I know about ampere's force law and all that, but I couldn't find an equation concerning permanent magnets. Obviously, two magnets with rectangular...

Greetings, I fabricated a PMA using vertically stacked stators and rotors. I tested the unit on a lathe and was able to gather the following data at different RPMs. The design uses the flux lines from both ends of the magnet. This configuration allows the stators and rotors to be stacked...

Hello everyone. There is a little project I could use some help with. I would like this done in a spreadsheet, so I can mess around with different values. The Problem: On one hand, I have a permanent magnet and, on the other, I have a ferromagnetic object. I want to find out the force...

what happens when a permanent magnet is wound with a copper wire (inductor) and the inductor is connected to some volatge? Will the magnetic flux of the permanent magnet increase (i.e., make the permanent magnet more strong)?

This is sort of a thought experiment. I want to find out if my approach to this is correct. How can I analytically find the magnetic field from a permanent magnet? My approach would be to consider the magnet to be a lattice, with each lattice point being a molecule with a magnetic dipole...

A lift electromagnet has N + S pole on the same side. will it push or pull a permanent magnet which has N & S pole on opposite side? If I have a lift electromagnet and a permanent magnet, both can pull 100 lbs. What is the break away force if I put them together? Thanks

Greetings, I have been working on a permanent magnet alternator, axial flux configuration. It has been configured with vertically staked stators and rotors. The traditional fabrication technique the stator is one large diameter with a large diameter magnet rotor above and the below the stator...

I am hoping someone here has experience with permanent magnets. I have a theory on how to size a permanent magnet for an alternator I am designing, and I want someone to confirm that my technique will yield a result that is useful enough to go through the expense of building a prototype. My...

The problem I am having is that I cannot seem to find the magneto-motive force of a permanent magnet. Most material tables give a Hc in kA/m, which I take to mean I multiply by the length of the magnet, then by the area of the magnet to get my total magneto-motive force. So does...

So I can't seem to find out why generators aren't designed so that the coils are passing in between TWO magnets N facing in and S facing out, and then S facing in N facing out etc. The flux density between two magnets is obviously greater and the flux lines are 'straighter' (more lines of flux...

What is the difference between permanent magnet fields and electromagnet fields?

I am trying to come up with a design that would track the position of a wire. The wire will have a permanent magnet attached to its tip. I will use a electromagnet to move the wire in only 1 dimension. Here is what I was thinking... I would put a stationary aluminum plate some distance from...

Hello, I'm building a DC generator for fun (of the cardboard and lego variety). It is based on this model: How would you calculate the power output from that, assuming we know the strength of the magnets and the frequency of rotation? Are there any easy ways to increase...

Hello! What is the lifetime of a permanent magnet? How we calculate it? Thanks

While working on a project I noticed something wonky and I don't understand how or why it is happening. Typically if I have an inductor, the presence of a permanent magnet will reduce the inductance according to its distance - however I have started using a type of nanocrystalline core that...

Hi If we have a Y shape iron and we put a Permanent Magnet N pole at the bottom leg of the Y in such that it will saturate it. would the top ends of the Y also be saturated. what if instead of 2 we have 20 branches where flux can go. what is the saturation will be like at one branch? thx

Hello, I've been extremely stuck on the following problems and was hoping someone could give me a push in the right direction: Homework Statement 1) Given an infinite slab of permanently magnetized matter of thickness d centered on the xy-plane with uniform magnetization \textbf{M} = (0, M...

Hi. I'm doing an experiment and I'm kinda stuck. I know that a current produces a magnetic field. In this experiment there is a current carrying wire (copper) and a permanent magnet suspended above it. Deflection is being measured as the current is varied. I know that both magnetic...

Does anyone know how to calculate the total energy of magnet? Thanks!

I know this may sound strange. Has anyone ever successfully created a working physical model of a magnet that exhibits the same properties ("flux" lines and attraction) without using magnetic materials or electrical influence? Thanks G

I am incorporating a solar chimney in my house build in Thailand, this will have a venturi to create the suction for removing warm air from the building and I intend to use this high air speed area to generate electricity. As air speed will be dependant on the Sun and not the more fickle wind...

What is the drag force on a magnet falling through a coil? I have found several sources online describing the drag force on a magnet falling through a conductive pipe. How might this vary if a coil is used in place of a pipe? Does the coil need to be connected to a circuit to create this force?

What happens, and why? (This isn't homework, just curiosity.) To be more precise, what would happen to the magnetic field of the magnet if we passed a current through it (assuming it is conductive). Will the current disrupt the magnetic domains? Will the magnetization disappear?

http://www.geocities.com/sc_cannon/filxb.bmp A wire carrying a current I has a magnetic field from a permanent magnet crossing it at right angles. The force on the wire is equal to the cross product of Current Length with the Magnetic Field, B. What is the force experienced by the...

When we magnetize a ferromagnetic material, we provide an input of energy. Is it possible to demagnetize a magnet, and convert a fraction of the energy to usable work? (Of course, this is not a useful way to generate work, and some fraction of the input energy is lost)

Hello, I'm a mechanical engineering student currently working on a project which involves a compressed air motor and a Permanent magnet DC generator. I have this generator : http://www.windstreampower.com/443905_PMDCG.php Basically, we'll use the generator power output to determine the...

I'm looking for an equation to calculate Tesla (B) between two permanent magnets with distance of 10mm. Magnets are located in front of each other; disk shape and intensity of each is 1.3T in its core, and 0.6T on surface, so I'm interested how to calculate the B between them in distance of...

G'day. I was wondering about the possibilities of making a permanent magnet hoverboard that levitates above a permanent magnet floor. They say that these new neodymium magnets can attract hundreds of kilos/pounds. Since repulsion and attraction forces are the same magnitude from what I hear, why...

I have been doing some experimenting with a relatively short cylindrical permanent magnet and a solenoid with DC current applied. I would like an explanation as to why these two things happen. The OD of the cylindrical magnet is just a little bit smaller then the ID of the solenoid. Placing...

Homework Statement The sketches below show a circular coil and a permanent magnet; the arrows indicate both the magnitude and the direction of the velocities of the magnet and coil. In which situations will the induced voltage (and hence the current) in the loop be zero? (Enter your answer...

Wind power is a force of nature and it has been used for centuries like for Dutch Windmills. Permanet magnets are a force of nature which through innovation have now been produced so well that they can now hold up to 500 times their own weight. That is a lot of power. The only...

Permanent magnets are advertised as having some scalar strength, say, 1.5 Teslas, depending on the composition of the magnet but not its volume. I'm confused about what this means. Shouldn't the magnitude of the magnetic field vary depending on where you measure it? And if I epoxy together two...

I have searched and searched but do not know what gives rise to a permanent magnet. I would like to know why two opposite forces are produced at the ends of the magnet. The closest I have got to it is to do with electron spins becoming aligned. Help would be most appreciated Thank you

Hi, What is the effect of "back e.m.f." on the torque output of a permanent magnet d.c. motor? I googled it but didn't get any results.. I just need a brief description to understand the concept.. Thanks :blushing:

I guess I do have to ask some questions on magnet storage. Especially over long periods of time. Basically, I want to know what the effects are if you store (relatively strong) magnets north to south with a slight gap in between (roughly 50mm between). N===S N===S N===S That's pretty...

I'm trying to make an interior rotating mangetic field that will induce electron flow in an encapsulated closed loop coil. What I'm constructing at this time (not finished yet) is a rotating (0 - 1600rpm+) neodymium permanet magnet setup in a Halbach Array assembly. I understand that inorder for...