Magnetism is a class of physical attributes that are mediated by magnetic fields. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. Magnetism is one aspect of the combined phenomenon of electromagnetism. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Demagnetizing a magnet is also possible. Only a few substances are ferromagnetic; the most common ones are iron, cobalt and nickel and their alloys. The rare-earth metals neodymium and samarium are less common examples. The prefix ferro- refers to iron, because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, Fe3O4.
All substances exhibit some type of magnetism. Magnetic materials are classified according to their bulk susceptibility. Ferromagnetism is responsible for most of the effects of magnetism encountered in everyday life, but there are actually several types of magnetism. Paramagnetic substances, such as aluminum and oxygen, are weakly attracted to an applied magnetic field; diamagnetic substances, such as copper and carbon, are weakly repelled; while antiferromagnetic materials, such as chromium and spin glasses, have a more complex relationship with a magnetic field. The force of a magnet on paramagnetic, diamagnetic, and antiferromagnetic materials is usually too weak to be felt and can be detected only by laboratory instruments, so in everyday life, these substances are often described as non-magnetic.
The magnetic state (or magnetic phase) of a material depends on temperature, pressure, and the applied magnetic field. A material may exhibit more than one form of magnetism as these variables change.
The strength of a magnetic field almost always decreases with distance, though the exact mathematical relationship between strength and distance varies. Different configurations of magnetic moments and electric currents can result in complicated magnetic fields.
Only magnetic dipoles have been observed, although some theories predict the existence of magnetic monopoles.
I want to record the displacement of a small magnetic ball moving sideways across the face of the sensor. I've had a close look at AMS's catalog of magnetic position sensors and I'm not sure how to choose one.
If I'm working with a movement range of <5mm and want a resolution of 5-10μm, and...
In a transformer, the primary coil has a current running through it which creates a magnetic field. Then this field induces a current in the secondary coil. That induced current creates a magnetic field exactly opposite the inducing magnetic field.
This might be an obvious question, but that...
Homework Statement
A proton moves with constant velocity in a certain region of gravity-free space.Which one of the following conclusions is valid?
A)There must be no electric field or magnetic fields in the region.
B)There could be an electric field without any magnetic field.
C)There could be...
I've posted this here because I think it might be related to the absoluteness of acceleration and rotation.
I've been educating myself on the Faraday Disk and was very surprised by one aspect of it. If we have a solid metal disk mounted on a shaft with two electrical brushes contacting the...
Homework Statement
Homework EquationsThe Attempt at a Solution
i have done the first two parts but the third part confuses me
i am assuming the current is flowing in the z direction then current is parallel to the magnetic field then why would there be a force acting on it ?[/B]
The equation needs to describe the force between two magnets and should relate to distance, angular frequency, angular acceleration, and torque. I need to find this equation for a research project, but I just can't figure it out and I can't find it online. (I'm new to this website so if this is...
This is one of the big confusions i have. When rotor magnetic field is 90 degrees with respect to stator magnetic field we get maximum torque. In field oriented control the a, b, c axis is converted to d and q axis. So making d axis to 0 and q axis to torque and running through pi loop does...
Homework Statement :A metallic disc of radius R is placed perpendicular to a magnetic field B.Both the magnetic field and the disc rotate with an angular velocity w about the axis of the disc.Find the induced EMF between the center and the circumference[/B]Homework Equations
Motional Emf=Bvl...
Homework Statement
A group of particles is traveling in a magnetic field of unknown magnitude and direction. You observe that a proton moving at 1.50 km/s in the +x-direction experiences a force of 2.25 x ##10^{-16}##N in the +y-direction, and an electron moving at 4.75 km/s in the -z-direction...
Homework Statement
A particle of mass 0.195 g carries a charge of -2.50 x 10-8C. The particle is given an initial horizontal velocity that is due north and has magnitude 4.00 x 104 m/s. What are the magnitude and direction of the minimum magnetic field that will keep the particle moving in the...
I have looked this up on several occassions and never satisfied.
It seems that either the answer keeps repeating magnetic or electromagnetic field over and over. Or the answer discuss the properties of electromagnetism.
Is the field a wave/particle like a photon ? Is it emitted like a photon...
I have this question which I need to solve . But I am unable to.
Suppose I have a current ring of radius R and current I (constant).
at a distance x from the centre of the ring, I have a iron disk (radius r and thickness t) present in the plane of the ring. This disk will be attracted to the...
What would happen if the entire Earth was somehow exposed to a massive magnetic field, such as those found near magnetars, like 10^10 teslas, for about 1 second? Would everyone instantly die? What would be the impact of a moving magnetic field vs a stationary magnetic field be? How much time...
Hi,
I have a problem with the fomular
u=m·B
and
u=B^2/4pi
Since I want to calculate how many magnetic energy on a solenoid, I couldn't decide which fomular should I use.
Homework Statement
Picture of the problem:
I first need to calculate the magnetic field in point P caused by the piece of wire at z = R (so the top wire parallel to the y-axis).
Homework Equations
[/B]
Biot-Savart law for magnetic fields:
##\vec {dB} = \frac {μ0*I} {4*π} * \frac {\vec {dl}...
Magnetic braking is a theory explains the loss of stellar angular momentum and is used extensively to describe the given rotation stars.
However, on a smaller and more directly observable level, when we consider Jupiter's rapid rotation rate of less than ten hours and its accompanying powerful...
I am a Graduate student in Electrical Engineering. I have to work on Electromagnetic, Dielectric, Magnetic field and Polarization for my project. But my problem is I do not have a good background in this course. Now, I really need it in graduate level. My question is, can you guys introduce me a...
my textbook says that electrons have a basic characteristic of magnetism just like charge and mass. this magnetic property in some materials adds up to result in a permanent magnet and in some others nullifies each other. how does it really occur? moreover if electrons hav magnetic properties...
Hi,
I saw this video and I can't explain why the magnet is propelled to the end of the coil with such a huge force. Can someone explain it in clear terms. I also tried to use Flemings left hand (or right hand) rule but it did not give me a satisfactory answer.
Thanks,
SM
Hi, for a particular project, I would like to create a 1~2 Tesla magnetic field in a stainless steel pipe along the z axis. I was wondering if my concept would work, or if anyone had better ideas.
Here's my concept.
Fig1. So I got a few pipes about 1 inch in diameter. I would like to have a...
I am trying to understand the basics of bldc motor. My question is if i am driving the 3 phase motor with sinusoidal waveform. The magnetic field is produced for each phase or it will add together to generate net magnetic field? How to get the net magnetic field.
We know a magnet has field with direction from North to South. Why when a piece of iron come close to the magnet can either be attracted and from both sites and not for example from one pole?
Homework Statement
Homework Equations
f = q.v.B.sin tetha
I = q/t = v/R
The Attempt at a Solution
(1) q =a.b.n.v.t is it right?
(2) I = q/t = abnvt/t = abnv is it right?
(3)F = q.v.B is it right?
(4) ?
(5) ?
is it right?
Hello ,
I am having a slight confusion while reading the chapter on Earth's magnetism . If we place a magnetic compass on the floor I.e on Earth's surface , the North (red) of the compass needle points towards magnetic north of Earth .
But would it be correct to say that "the compass needle...
The think is that I would like to create a magnetic trap "minimum of magnetic potential energy in all 3 directions of space" using a distribution of magnetic dipoles as a field generator.
In other words, I would like to know if setting in some way some magnetic dipoles is possible to create a...
Even if the outer core is convecting and conductive it is still charge neutral, so how can a Magnetic field be generated? Maxwells Equation say there needs to be net charge moving for a Magnetic field to be generated.
I am computing magnetic field around a thick conductor to do railgun force modeling. I am currently re-examining my magnetic field computation, and I have found some confusing results stemming from a fairly simple use of the Biot-Savart Law. The main issue is that the more nuanced application of...
Hi,
I would appreciate it if someone explains the difference between these two phases regarding a coil rotates in a uniform magnetic field.
1. The rate with which the coil intercepts the lines of magnetic field in the dynamo is maximum when the plane of the coil is parallel to the lines of the...
Homework Statement
Multiple-choice question:
Homework EquationsThe Attempt at a Solution
I know that the induced emf is maximum when the coil is parallel to the direction of the magnetic flux, so I should choose either B or C, and I have read the the rate by which the coil cut the magnetic...
Homework Statement
Griffith ( Introduction to electrodynamics , 3 ed.)
says in Problem 7.9:
An infinite number of different surfaces can be fit to a given boundary line, and
yet, in defining the magnetic flux through a loop, Φ = ∫B.da, I never specified the particular
surface to be used...
muons mean lifetime of 2.2 µs
muons in a strong gravitational field or traveling at relativistic speeds experience time dilation
would a muon in a strong magnetic field, say near a magnetar experience additional time dilation more than a muon in an non-magnetic field with the same...
Homework Statement
Uniform magnetic field ##= Bt## exist in cylindrical region of radius ##R## is pointing into the plane of figure (as shown in figure). A frictionless groove of length ##L## is fixed symmetrically from the centre O at a distance of ##\frac{L}{2}## .A charged particle of mass...
Hello everyone,
My question is between theorie and practical (so I'm still wondering if it's the right place). I'm reading Serway and Jewett. There's an example about the magnetic flux through a rotating bar and so and induced emf. I understand this emf will be equal to the the opposite of the...
I am trying to understand the magnetic dipole field via loop of wire.
The above pictures show how this problem is typically setup and how the field lines are typically shown.
The math is messy but every textbook yields the following:
β = ∇xA = (m / (4⋅π⋅R3)) ⋅ (2⋅cos(θ) r + sin(θ) θ)
The...
Hello, and thanks in advance for taking a look at my question.
Generally, I am trying to make a railgun force model. Since railguns depend on the magnetic field created around the rails (and the resulting Lorentz force) I need to model the magnetic field created by the current that flows...
Hello
Today we did a lab and one of the activities was having a compass underneath a wire while the current was off. The wire was straight so that it was directly aligned to be with the needle of the compass. One the current was flowing, the compass arranged itself in that it was not exactly 90...
Homework Statement
I had know that for finding magnetic flux is NBA cos theta. The answer is C though, so why is it sin theta instead of cos theta? I wonder
Homework Equations
BA cos theta
NBA cos theta[/B]
The Attempt at a Solution
Hi
I'm thinking about making an instrument to show the force on a wire carrying electric current for students in lab. A normal wire which levitates from ground after it has current flowing in it.
We have the following equations
F = ILBsin(a)
W = ALg
'A' being the mass of unit length of the...
Hi,
I have a question about steel, for instance, silicon steel used in magnetic cores.
I was wondering about how Iron magnetises: can you align the grains/domains and heat treat it [or anything], so that it responds differently to flux one way then the other direction?
For example, say you...
Let us consider the following thought experiment.
There is a magnetic field in free space produced by a steady current, hence solution of the (magnetostatic) Ampere's law Curl H = J.
There is also a material with some parameters ε and μ and no currents, where the Ampere's law is Curl H = 0...
Homework Statement
Question asks for the flux through the loop when the loop is both perpendicular and at an angle to the solenoid.
solenoid diameter = 2.2 cm
loop diameter = 6.8 cm
B inside solenoid = 0.22 T
Homework Equations
∫B⋅dA = Φ_B
The Attempt at a Solution
B is constant so can...
Hi,
I'm currently investigating magnetic fields/their cause. This has inevitably led me to learn all about electrons. Here I want to post my understanding on electron 'spin' so people can correct me if I'm wrong/help others get a better understanding.
So I watched this YouTube video for...