A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, cobalt, etc. and attracts or repels other magnets.
A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include the elements iron, nickel and cobalt and their alloys, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Ferromagnetic materials can be divided into magnetically "soft" materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically "hard" materials, which do. Permanent magnets are made from "hard" ferromagnetic materials such as alnico and ferrite that are subjected to special processing in a strong magnetic field during manufacture to align their internal microcrystalline structure, making them very hard to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied, and this threshold depends on coercivity of the respective material. "Hard" materials have high coercivity, whereas "soft" materials have low coercivity. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization.
An electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Often, the coil is wrapped around a core of "soft" ferromagnetic material such as mild steel, which greatly enhances the magnetic field produced by the coil.
I have ordered a spool of wire with these properties:
NEMA-MW-80 155C This magnet wire has a copper core with a dual film of polyurethane (85-90 percent) with polyamide(nylon) as an outer coating making up the other 10-15 percent.
.0169 inch diameter
rated to 155 degrees centigrade...
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 need to calculate how much voltage is created as a magnet passes over a coil. However I don't know a formula to calculate this.
Could anyone help me, I just need a formula
PS: sorry, spell check does not work
I was wondering if it was possible to bend a beam of light with a magnet. If this is possible could someone tell me what the requirements for the magnet be to do such a thing.
I used the formula here:
http://en.wikipedia.org/wiki/Magnet#Force_between_two_bar_magnets
The values came from an experiment in which I found the force between two small Neodymium magnets by balancing with the force of gravity (it was around .15 Newtons). Am I using this equation...
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...
I have a cylindrical neodymium magnet. I know that the magnetic field varies with distance, but how would I determine the magnetic field B at a certain point, through experimentation? I know how to find the force between two magnets at different distances by balancing out with gravity, but I'm...
I would like to know..what is the concept of rotating a magnet above a coil of wires to produce electricity.. what is the factor affects the power of electricity produce..
1)Is it the number of coil?
2)is it the power of magnet?
3)is it the distance between magnet and coil
4)or anything...
I've been building an electromagnetic wheel (a bike wheel which rotates by electromagnetic interaction between electromagnets on the hub and permanent magnets on the rim) and I've come across an interesting problem. Currently, I've got the electromagnets mounted on the hub with the coils pointed...
To my surprise, through experimentation, I have found that the "Flux tubes"/lines of force, do not move when the magnet is turned on its' axis but the field lines do move with the magnet when one flips it from N to S. This would lead me to conclude that the N/S area are a property of the poles...
1. is insulated wire ok to use on an electromagnet?
2. say you have an electro magnet in the form of a spool of wire with an iron core, would it be possible to wrap the entire assembly in a material that would contain the magnetic field produced by the current flow?
3. what is the strongest...
Does anybody know of an online application, or a program, or anything that can simulate accurately magnets and how they interact? Like a simulator.
Thanks very much. ^_^\/
If I get this whole “Moving magnet and conductor problem” business at all, one frame’s electricity is another frame’s EM wave. So moving a magnet causes an electromagnetic wave, AKA: photon. I assume the faster you move it, the higher the energy of that wave/photon. (Maybe you have to vibrate it...
Homework Statement
For a magnet of length l = 16 cm, cross-section .25 cm^2, and magnetization M = 7.8x10^5 A/m, estimate H and B at the midpoint.Homework Equations
Unsure if any of these equations are relevant, but these are the ones that I've tried.
q_m = MA
B = \mu_0 M
\mu_0 H = \mu_0 MThe...
hi..i know the faraday's electromagnetic induction e=-dФ/dt...supposing there is an coil of wire and i am accelerating magnet through the coil of wire and this will produce emf because accelerating magnet results in change in magnetic field...my question is how to relate this acceleration a and...
Hello, please forgive my ignorance. I need help coming up with a formula I can't seem to find on the internet. Assume I have a magnet that can attract a maximum of 5kg iron sphere against gravity from a distance .2m. My question is how much could that same magnet attract at a distance of .1m...
Homework Statement
A coil of radious 4cm has its plane perpendictular to a uniform magnetic field of strenght 2 mT directed into the page as in the following diagram
http://i83.photobucket.com/albums/j283/cowsgomoo47/physics_prob_magnetism.jpg
The magnetic field is then switched off is...
Homework Statement
How do I calculate the magnetic field of an irregularly shaped permanent magnet?
Homework Equations
Field of a magnetic point dipole:
\vec{B}(\vec{m},\vec{r}) = \frac{(\vec{m}.\vec{r})\vec{r}-\vec{m}\left\|\vec{r}\right\|^{2}}{\left\|\vec{r}\right\|^{5}}
where
\vec{m}...
Ok so, i think this is kinda a basic question but here goes. I am building a machine that uses magnets and desperately need to eliminate a zero point so the movement will be smooth so what i need to know is if you have a magnet being attracted to substance Q and the magnet has a 3cm distance...
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...
I was watching this video on youtube called will it blend where they supposedly blended neodymium magnets into powder. I saw sparks coming from the process of it being powdered but I have read elsewhere that trying to file neodymium magnets is dangerous as it would be explosive.
I am not sure...
would like to ask, is that possible to generate electricity without using available electric and magnet?
is that if we don't have magnet, we wouldn't have electricity?
could the positive or negative field be gathered without using the magnet?
I want know that lifting magnets for lifting a lots of cars ; so it use energy or not?
Why a lifting magnet use energy?
It can only have a static force with his superconductor !
Why that superconductor use energy(electricity) for his static force?
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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...
hi there ,
When a North Pole of a magnet is made to oscillate in the direction of Earth's North Pole magnetic field.
Also When a south pole of a magnet is made to oscillate in the direction of Earth's north pole magnetic field .
I then measure both of there period of oscillation
When doing...
i29.tinypic.com/25ppfth.jpg
Can we build it without any inequality and without any jagged ?
i want all flux work as well as picture
can we build this radially oriented magnet?
Hello,
(I'm not fluently in english, sorry if it's not a pure english)
I use FEMM software for caculate energy. I have found an integral fonction "Magnetic field Energy" when I select a surface. But I have always the same energy, I don't know why. Is there necessary to make something...
Magnet near a "magnetic" black hole
Hi,
If I were to bring a magnet (just 1 mm long) close to a hypothetical "magnetic" black hole - something that has such an incredibly high permeability that it draws all the magnetic field lines from the magnet's pole toward it - and if this latter object...
Homework Statement
A bar magnet experiences a torque of magnitude 0.075 Nm when it is perpendicular to a 0.50 T external magnetic field. What is the strength of the bar magnet's on-axis magnetic field at a point 20 cm from the center of the magnet?
Homework Equations
\tau = \vec{\mu} B...
Homework Statement
A copper penny falls on a path that takes it between the poles of a magnet. Does it hit the ground going faster, slower, or at the same speed.
The Attempt at a Solution
Clearly the penny undergoes a change in magnetic flux. Since it receives a change in magnetic flux...
The strength of magnetic force varies inversely with the square of the distance between the magnets. In other words,
Force = k/(distance^2)
Suppose that when two magnets are 4 cm apart, there is a force of 4 Newtons. Find the work required to move the magnets from a distance of 3 cm apart...
Can anyone check if I answered these questions correctly? Thanks a bunch!
1. The N pole of a bar magnet is pointed in along the axis of a horizontal, continuous coil of wire. When the magnet is quickly roated about a vertical axis until the opposite end of the madnet points into the coil...
Magnetometer is used to compute the magentic moment of a magnet. In this procedure, we are asked to record the angles of deflection on both sides of the compass heads (that is North and South poles of the compass), since they are vertically opposite angles, they should read the same. Why are...
Hi! This is my first post on this forum, and I have two questions.
First of all I'd like to mentoin that my math knowledge is at high school level + some basic calculus. Ah, and I haven't learned about (partial) differential equations yet.
My physics skills go only as far as electromagnetism...
What property of the magnet determines which side of it is North and which side is South?
I know that we are unable to separate the poles of a magnet (ie cut a magnet in halves and we get two magnets). How come?
Is it possible to make a magnet move constantly up and down, insider a container for example, without touching it or forcing it to move?
I don't know much about Physics but wanted to ask this question as its been bothering me for a few days!
I was thinking about how magnets may repel and...
Ok let's say we have an infinitely long magnet, with poles arranged like in the diagram. A positively charged particle is moving as shown in the diagram. Because of Lorentz forces, the particle will be accellerated towards you. Now change the frame of reference so that the particle is stopped...
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
A 10-cm-wide, zero-resistance slide wire is pushed toward a 2.0 ohm resistor at a steady speed of 0.50 m/s. The magnetic field strength is 0.50 T. How much power does the pushing force, 6.25*10^-4 supply to the wire? What is the magnitude of the induced current?
I got 3.13*10^-4 for the...
If a magnet is used to levitate another magnet (using the force of repulsion) can it be considered as doing "work" in opposing the force of gravity? If yes then why does the energy required to do this "work" not diminish over a period of time?
[SOLVED] Tension in a string of a object being pulled by a magnet
Homework Statement
An Iron bolt has a mass of 65.0g and hangs from a string 35.7cm ong. Top end of string is fixed. Without touching it, a magnet attracts the bolt so that it remains stationary displaced horizontally 28.0cm to...
A magnet will induce EMF when it passes through a conducting coil. Where does that energy come from? Does the coil do work on the magnet somehow? The B field induced in the coil should be parallel to the magnet's motion, so I would think it could not slow the magnet's progress. Does the magnet...
Hello,
Suppose you had an iron magnet. What effect would an electrical current have on this magnet? Would it still retain its magnetic properties?
Thanks in advance for the help.