Magnet Definition and 868 Threads

a barmagnet seems to be a densly winded solenoid just with the exception that the field of the solenoid is allmost zero outside and also at its ends but strong in the inside witch doesn't agree with barmagnets

Help me explain how the "magnet dropped down a copper tube" demo conserves energy I've tried explaining to this person that the potential energy you give a magnet when you do work against gravity to raise it up to the copper tube is all the energy it has to deal with, and once dropped down it...

Hello. I would just like to begin by saying that I am very aware of the vast complexity of the subject of magnetism. Still, I have been hoping to find a way to get a basic idea of how much a magnet and an electromagnet are attracted or repelled by one another. I do not need highly perfect and...

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...

I think magnet has to be a conductor of electricity if is made of iron or steel. So, What happens when we pass a direct current through a magnet? What if we pass through AC? Does the passage of current effect the strength of the magnet?

Recently while working with electromagnet , we noticed one thing. I we bring strong magnet near very weak PM or electromagnet, It will attract the weak one whatever is the polarity of magnets. we increased power to electromagnet then it was giving repulsion. I did't understand this...

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

Has anyone ever considered this issue with magnet falling in copper tube?? Homework Statement I must explain why a magnet falling in a copper tube slows down. Homework Equations F = B^qv However, I must *explain* this, I don't have to calculate anything The Attempt at a Solution...

I have been wondering how to calculate how much current and voltage would be induced through a 2m length of coil when a magnet passes through. The coil being 30mm in diameter with 1mm thick wire coiled around 200 times (for ease of calculation so cable would roughly be 18.8m long) with a...

I have a question about a magnets position over a coil of wire in an A.C generator. Is the voltage in the coil at Peak as long as its covered by the magnet? and then the voltage starts to decrease to 0 volts as the magnet starts uncovering the coil until the magnet totally uncovers the coil and...

Homework Statement What is the force from an infinitely long cylindrical magnet on a magnetic dipole? Homework Equations M=Mz (given in problem) The Attempt at a Solution My argument for this solution that since the magnetization is in the z direction and the cylinder is...

i'm sure we have all seen the little torches with a magnet inside that you shake to generate the required electricity to power the bulb... we were talking about them in the pub the other night and the following question came up... my question is this, will the magnet ever "run out", and by...

Lets say we have a spherical shaped and very powerful magnet. Let's say it has a 3" diameter and has some good weight to it. What would happen if you spun the magnet at great speeds. Let's say for the sake of argument say some 300,000 RPM. Could the centrifugal for created by the spinning...

If I had a strong magnet and was standing in metal shoes that were welded to a metal trashcan lid, could I levitate myself with said magnet?

Let's say a magnet is attached to an object that weigh's 15 pound's . Then someone attempt's to take the magnet off the object . The object then go's up with the magnet (still being attached to it ) Does that mean the magnet can lift 15 pound's ? Also when a magnet is rotateing through a coil...

I am looking to build a NEO magnet magnetizer for RC motors. Currently we are having issues with the motors losing magnet strength after they are run. The rotors to replace are $30+. In the Old days, we ran brushed ceramic magnet motors. With these, we had a magnetizer to simply zap the motors...

Hey all, I'm new to this site, so bear with me here! First post woot! Homework Statement A bar magnet with magnetic dipole moment 0.5 A m2 lies on the negative x-axis, as shown in the diagram. A compass is located at the origin. Magnetic North is in the negative z direction. Between the bar...

I have been thinking about a bar magnet and an infinite wire in free space. The wire is positioned below the north pole of magnet and carries a current. 1) The force from the magent on the wire: Due to the magnetic field, the Lorentz force on the electrons in the wire creates a force on the...

I watched a video there about cathode ray tubes and the guy in the video demonstrated the negative pole of a magnet deflecting the beam and the positive pole attracting the beam. I know that moving electrical charges create magnetic fields but I didn't know their magnetic fields always deflect...

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...

Has anyone heard of a permanent magnet in the shape of a ring or toroid with no poles? I believe that one could be made by winding a ring of magnetic material, such as steel, with a wire winding, like one winding of a toroidal transformer. DC current could then be passed through the winding...

Since light consists in part of magnetic fields, I was wondering why the magnetic field of a magnet never has any effects on the light passing through it. Is it because the magnet's field is static while the light is moving?

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...

I consider two magnets of smae pole strength and length. If i bring either of similar poles of the magnet forcefully near and stick with a glue. Is the combination a magnet with three poles? Thank you for your help

i would really appreciate if someone could help me out with this one. i m preparing for an exam and this question is a question from papers of previous years and its bugging me because it seems very specific in that i can't seem to find anything like it in textbooks. what i m mainly stuck on...

i would really appreciate if someone could help me out with this one. i m preparing for an exam and this question is a question from papers of previous years and its bugging me because it seems very specific in that i can't seem to find anything like it in textbooks. what i m mainly stuck on...

I read interesting article regarding Halbach arrays and magnetic levitation (see [PLAIN]www.lmco.cn/data/assets/9197.pdf[/URL]). In the article (see equation 1) the author states that the voltage generated by moving magnet over rectangular coil is V= L*dI/dt + RI = \omega \Phi cos(\omega t)...

I need some help to calculate the retardation of a magnet cylinder passing trough a coil with an open end which lies horizontal. If you have a 0.5 m long circular coil which is 50 mm in diameter and a circular magnet cylinder fitting into the rod. The magnet cylinder has an initial speed of 10...

My question is that can we make a metallic particle revolve around a magnet ,like planets revovle around a star or electron around a nucleus...e.g can iron grainy particles revolve around a powerful magnet ?

hey guys, i was wondering if there was a formula to measure the strength of a magnet in relation to its size, and what else is needed to be known before such a value can be computed. e.g. its shape, let's say a bar magnet(you have my apology if i have posted in the wrong forum, but I'm...

If the magnetic poles are at the ends of a perfectly symmetric permanent magnet cylinder and and you spin the cylinder around its central axis, will anything happen to the magnetic field? I feel like something should happen since the magnetic domains are revolving around, but the field is...

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

Homework Statement A long bar magnet is bent into the form of a closed ring. If the intensity of magnetisation is M, and ignoring any end effects due to the join, find the magnetic field H and the induction B: (a) Inside the material of the magnet (b) just outside Homework Equations...

I am a teacher and am in the process of developing labs dealing with magnets. I have seen calculators on the internet that can calculate the pull force in pounds for a magnet when provided the shape of magnet, thickness, diameter and Br value in gauss. I have failed to find the equation used...

why Earth behaves as a magnet

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...

Homework Statement I'm given two identical pieces of metal (in size, shape, color, density, etc.) and no other materials to work with besides my hands. Using only those two pieces of metal and my fingers, I am tasked with determining which of the two pieces is a permanent magnet (the other is...

I've attached a diagram of a bar magnet being plunged into a solenoid. I'd like someone to explain the direction of the current please. Why do both arrows indicating current move upwards? Using the right hand grip rule i understand the north pole being in the position it's in. I get a...

After a demonstration, my professor placed a metal plate over the two ends of a horseshoe magnet in order to prevent it from attracting other materials. I was wondering if this has to do with there being some type of "magnetic resistance" between the poles, where it is easier for the field to be...

A permanent magnet of mass m is located on the vertical axis of a stationary, conducting , non-magnetic ring for a long time. The ring has a radius a, resistance R and inductance L.At time t=0 the magnet is released. Suppose the magnet has dipole moment \muz. Write down the equation of motion...

Preface: If a bar magnet is cut in half, we are left with say N-S--cut--N-S allinged along the z axis. Then the S and N ends are attracted to each other. This attraction is due to the "fringing" or non-uniform B field of the poles. That is the component of the B field that is normal to the...

I understand how to figure the magnetic field of an air core electromagnet, but apparently bitter magnets are slightly different. I've looked around and couldn't find equations on the site for the lab in Florida. If anyone could help me out I would be grateful :D

Hello all! I'm new to this site and new to electromagnets. I've done some research but now i need help from anyone who is willing. I'm playing around with electromagnets and neodymium magnets. Now i want the electromagnet to repel the neodymium. So first thing I can't use a ferrous material...

The multiple coils superconducting maget is uaually quench protected by bypass diodes. The heat spreading model is mentioned on textbook for coil to coil quench spreading. But the heat spreading is not fast enough for magnet quench protection. Because the theoretical quench protection...

Infolytica MagNet help! hi there, i'm trying to simulate a transformer using Infolytica's MagNet. But I'm not getting it right. Mostly because i couldn't find any tutorials or examples for this program. Can anybody post a tutorial link or even a example(s) where there are coils designed...

Homework Statement Suppose a straight 1.00-mm-diameter copper wire could just "float" horizontally in air because of the force due to the Earth's magnetic field, B, which is horizontal, perpendicular to the wire, and of magnitude 5.0 x 10^-5 T. What current would the wire carry? Does the...

hi all, i am currently working on a magnet generator/motor and i have some qns on electromagnetism. i am currently trying to find out how much does my electromagnet (ferrite core) requires in order to repel a permenant magnet, in this case, a cylindrical NdFeB magnet. i have been trying to...

1. When liquid oxygen, being paramagnetic, is placed in a magnetic field it possesses magnetization in direct proportion to the field strength. 2. Does this mean that it emits a magnetic field and is itself a magnet while in this field 3. or is it just a part of the larger magnetic...

Hello; When you cut a magnet that has north and south poles, you get two magnets with north and south poles. If I cut a million magnets out of it, each of those magnets will have north and south poles. However, what happens when I cut down to the last electron? Will that electron still have a...

the theory magnetic field is produced by moving electric charges the field is proportional to the quantity and velocity of those charges the velocity of electrons is about 1mm/s at 15A/mm~2 in copper the velocity of a cd spinning is about 1000RPM 6m/s 6000 times more the the speed of...