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.
Can magnet fields deflect displacement currents?
Could displacement currents be made to propagate in spirals like those in a cyclotron?
Do they travel close to the speed of light?
Can they be focused into beams?
Can they transmit electrical energy at a distance?
Are they subject to the same...
Hello!
I don't understand one easy moment in high temp solid oxydes fuel cells (SOFC):
1. Oxygen ions are moving always via solid electrolite ZrO2? SOFC without load and SOFC in short circuit modes. (High temp is default mean)
2. Electrolises process need electric energy and external...
Homework Statement
I want a box shaped robot to move on the ceiling. The robot sticks to the ceiling using magnets. I am attaching a picture. The red is a magnet. How do I calculate how much force is needed to move the robot horizontally? I know very little physics and I need to figure out how...
Hello
8 months ago we discharged a 3 Tesla superconducting magnet which is part of old FT-ICR mass spectrometer. Magnet was charged some 20 years ago and working since (which is exceptionally long since it worked in persistive mode, which means no charging in all this time).
During...
As we know magnet can attract iron, but not aluminium,
does anyone have any suggestions what make aluminium behave differently in term of molecule structures? such as Electrons, Photons Neutrons ...
Thanks in advance of any suggestions
A bar magnet with uniform magnetization is inserted half way into a solenoid, and I am wondering what the force is on the magnet?
The magnet's magnetization is pointing up, which means it has bound surface current circling counterclockwise, and a magnetic field pointing up.
The solenoid...
I was wondering if there was a way of having a magnet near an audio cable without having any interferance maybe by using a sheild.
My idea was to have a magnet to replace the 3.5mm audio jack in a headphone cable and port so that it would magnetically attach.
Is this possible?
I'm trying to approximate forces on a system.
One of my Forces is a 6x8x1" Ceramic Grade 8 magnet on an ferromagnetic object, but they are separated by a small space (about 3/16").
I know the Pull of the magnet, but is there a way to calculate the pull of the magnet relative to the...
I have a situation that a magnet is placed near to a coil. Especially in pumps and the pump is working based on the stroke mechanisam. The coil is powerd up by a DC source of 12volts and the piston(which having magnet on it) is attracted by this coil called as stroke. The distance between the...
can someone help with this calculation
two semicircle magnets N-S of strength 'B' encircle a solenoid of length 'L' and move with a constant velocity 'V'. what will be the current 'I' that is induced in solenoid. also, what force will the magnet experience because of this current (Lenz's law)
IYPT Question--Coin and Magnet
I don't really need an answer.
I just need someone to guide me or tell me what I need to study on.
Or if you have any ideas on this question, feel free to express them.
Place a coin vertically on a magnet. Incline the coin relative to the magnet and then...
Hi
Sorry I'm not good in physics at all.
I have the following dust problem becoming attached to Nickel coatings.
from what i know Nickel can become magnetic
but aluminium should not be attracted to magnets.
I did an experiment to confirm if the nickel coat is acting as magnet
in...
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...
hi, I was wondering if there is an equation out there that let's you calculate the force between two neodymium magnet. thanks, i would really appreciate an answer.
Homework Statement
A slender, 200- g bar magnet 15.0 cm long has a magnetic moment of 5.50 A m2. It is held at an angle of 45 o to the direction of a uniform magnetic field. When released, it begins to rotate about its center with an initial angular acceleration of 8.40×103 rad/s2. What is the...
I'm trying to learn the basics of designing superconducting magnets for guiding particles, but I'm having a hard time knowing where to start. I don't have a background in this field (besides EM classes). Right now I'm thinking about ordering "Superconducting Magnets" by Wilson and studying...
I am trying to understand the magnet and conductor problem that Einstein mentions at the beginning of one of his 1905 papers.
In the frame of reference of the conductor, the magnet moves. Why does this mean that Faraday's law is applicable and not Lorentz force law?
In the frame of...
Homework Statement
A person throws out the back of a car a strong magnet that is attracted to the metal of the car. Will the magnet return and stick to the back of the car or fall to the ground? The initial velocity of the magnet is v=sqrt(5)i m/s. Treat the magnet/car interaction as an...
If a magnetised neodymium ball has a definite north and south point, could you slice the ball in two, and weld 2 "north" halves together, to create an entirely north ball? If this is impossible, how about designing a ball made in, say, a 3D printer, then embed it with small magnetised neodymium...
Hello everyone,
as you may notice I am new to this forum. Unfortunately I've been stuck on a small problem for a few days and I can't seem to find the solution.
It appears to be a simple problem so I am hoping that someone here, with a bit more electrical engineering background as myself...
If you had a lined retangular section solenoid inclined at a angle of 45 deg and you rolled a rod magnet ( just fits inside the retagular section) down it. Would the current induced in the solenoid brake or accelerate the rod magnet.
alright so i think I've got a pretty good handle on this, I am looking for a proof read though. any acurate input is greatly appreciated :D
Field intensity in teslas = (amps x turns)/coil area; ignoring coil length effects
meaning
B=μ0(Ni)/m^2
right? but my question is: don't i have...
A magnet that won't stop spinning??
what happens if a horseshoe magnet is fixed to a a coil such that there is a constant field through the coil?? The initial torque due to the field will spin the coil,but since the magnet is connected to the coil,it will keep sending a field through the coil...
Hi,
I wanted to calculate the magnetic field of a cylindrical magnet at a point P (r,ɵ,z). The magnet can be at the origin or anywhere convenient. Preferably the axis of the magnet is aligned with the z axis.
The magnet is of radius r_m and height h_m. The remanent flux density of the...
I was trying to find the value of the magnetic field at a distance x from a rare-earth magnet and came across this equation:
B=\mu_o*2\mu/(4\pi*d^3)
Does anyone happen to know the magnetic moment, \mu, of a rare-earth magnet? Nothing specific, an order of magnitude value is fine.
Thank...
Is it possible for one magnet to attract another over a distance of 1m? To specify, if magnet 1 was at point A on the East side of the ruler, and magnet 2 was stationary at point B on the West side of the ruler. Could magnet 2 attract magnet 1 so much that both were bound together at point B on...
Hi,
I've just completed a prac, where a beam was placed into a solenoid with a current flowing through it, causing a force to exerted down and I balanced out the force by placing weights on the other end in the effort of calculating the magnetic field strength. Anyway, one of the short answer...
Homework Statement
An alien civilization has crossed the galaxy to invade the Earth and enslave humanity, again. Their attacks have been successful so far because their assault troops are equipped with handheld weapons that project beams of charged particles (protons & electrons) at very...
I am trying to do a pre-lab assignment for an introductory calc-based E&M course, and it involves the calculation of a magnetic field due to a bar magnet.
My first inclination was to use the B = (mu/4pi) * (q (V x R ) / R3) equation, but I am quite certain that this is not the correct...
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...
I'm doing a lab write-up for physics 2. The experiment is about the title, a bar magnet being dropped through a solenoid.
I have to explain four graphs that plot the change in emf (y axis) vs. time (x) axis. There are incoming and outgoing peaks on these graphs. I have to tie these results...
I'm doing a lab write-up for physics 2. The experiment is about the title, a bar magnet being dropped through a solenoid.
I have to explain four graphs that plot the change in emf (y axis) vs. time (x) axis. There are incoming and outgoing peaks on these graphs. I have to tie these results...
new guy here with a simple question.
if i were to coil 10 turns of 14 gauge insulated wire around an 1/8" round x 1" long neodymium magnet, then wire it in parallel to a second magnet with 20 turns of the same gauge wire, what kind of change could i exspect in the second magnet if i spun a...
a steel top which remains upright when not spinning has an electromagnet pulling on it from the side. Q=does it make any diff how much the emagnet moves the top sideways if the top is spinning or not? Please dirregard the friction factor at the bottom point of the top. thanx
Hey guys,
Im trying to design a electric gear shiftier for a motor bike. Basically I require about 200N of force to change gear with a 10mm throw (in both directions). I would like to use a tube neodymium magnet. (23mm diameter 25mm high with a 5mm hole throw the centre with a N48 grade)
What I...
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...
Hey guys,
Im trying to design a electric gear shiftier for a motor bike. Basically I require about 200N of force to change gear with a 10mm throw (in both directions). I would like to use a tube neodymium magnet. (23mm diameter 25mm high with a 5mm hole throw the centre with a N48 grade)
What...
Homework Statement
1. compare the induced voltage of the attached magnet ( two like charges) with the induced voltage of one magnet only?
2.compare the induced voltage of attached magnet (opposite poles) with one with only one magnet
Homework Equations
The Attempt at a...
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)?
Magnet attached to boat, would it work!?
OK,
if there was a boat with a magnet held in front of it by some sort of arch/crane attached to the boat would the boat be pulled towards the magnet, thus moving the boat forward, or would it just stay still.
______
o [________]...
Hi!
I'm a new face here and have an easy question.
I know how to calculate induced current when magnet moves through coil (it's E=BLv) but how do you calculate how much a magnet will decelerate when it goes through the coil? Will it decelarate at all?
I have one of those mechanically-powered...
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?
I have 1 week to build a motor.
I'm looking at building a homopolar motor.
I know I need a magnet. But does it have to be a neodymium one? And is Amazon a good place for such magnets?
And does the screw have to be a ferromagnetic one?
And if anyone has built such a motor, some hints and...
My question is:
does a north pole attract or repel a piece of metal ?
My attempted answer is:
I think that the north pole alone would not attract a piece of metal. Instead it would require the north pole in conjunction with the south pole to attract a piece of metal.
Can someone please confirm...
I have a bunch of rare Earth magnets that I bought a few years ago. For the most part, they've been rather haphazardly stored in a jumbled mess, with a few others stuck on the refrigerator. Today I noticed that at least some of them are noticeably weaker (particularly noticeable with the...
I came across a couple of cow magnets a while back.
When you drop a cow magnet down the center of a vertical piece of steel conduit, it doesn't drop as fast as it usually would.
When you drop a cow magnet down the center of a vertical copper plumbing pipe (closer fitting than the conduit)...
Hi PF,
A disclaimer, I am no good at Physics or math.
My question:
When calculating the pull force between two magnets it seems to always be calculated at an angle perpendicular to the surface of the magnet.
I was wondering what effect on the force required to "pull" one magnet away...
I have just learned electromagnetic induction and it states that if you move a magnet through a solenoid, you would get an induced current.
Say, if you have a copper solenoid, and if you want to move a magnet through it, there will be something (maybe, a force) that would prevent the magnet...