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.
To my understanding, photons have no charge, so how does the magnetic field control them.
Also side question - in the diagrams I see the photons seem to kind of curve around the magnetic field, does that mean they are accelerating?
Homework Statement
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I have been given an equation for the magnetic potential of a buried magnetic object which is as follows
Pm=α/x2
Where α is some constant and x is the distance from the magnetic body.
I need to derive an expression for the magnetic field strength at some distance x...
Let's say that there's nothing else in this universe except for 2 charged particles: q1 and q2.
q1 is moving relative to q2, moving at velocity v. I've read that a magnetic field is made by a moving charge. In this case, the moving charge q1 is moving relative to q2. What would the magnetic...
Homework Statement
The circuit in Fig. 32-31 consists of switch S, a 12.0 V ideal battery, a 20.0 M resistor, and an air-filled capacitor. The capacitor has parallel circular plates of radius 5.00 cm, separated by 3.00mm. At time t=0, switch S is
closed to begin charging the capacitor. The...
Hello!
I've made a lot of research about measurement of high magnetic fields - such us 1T - 2T and I can't find sensors for this range.
I'm looking for a hall sensor with which I will be able to measure 1T magnetic field with good accuracy - about 0.1 mT. Do you know about anything like that...
1. Why is Earth's South Pole called its North Pole? Why hasn't it been changed to make it more scientifically accurate?
2. Why are the North Poles of other planets defined relative to Earth's 'North' Pole? Why isn't it based upon the actual direction of the planet's magnetic field?
Hello everyone,
This is my first post here
Firstly, I'd like to start by saying that it's my best intention to follow the rules on this forum. Therefore, if I've posted this in the wrong section please forgive me, I will try and learn the ropes quickly.
One of my students has given me some...
So I know if you move a charge in a magnetic field it induces voltage and hence a flow of charge is created which is current. ( Please correct me if I'm wrong). But that's pretty basic right. However, I'm having trouble understanding the use of split rings in the functioning of a motor. I would...
Homework Statement
In Fig. 32-9 there is a + x-directed uniform magnetic field of 0.2 T filling the space. Find the magnetic flux through each face of the box shown.
Homework Equations
ΦM = B ⊥ A = BA cos θ
The Attempt at a Solution
My attempt is attached to this post. How do I determine which...
HI,
I have application where i need to lift metal plate, 3kg weight, ( 3mmX 15mm), 250degree.C hot, for the period of 1min and put it back. For lifting purpose i am using actuators. As i have no opportunity to make hole in plate i have to use magnet for lifting purpose. I got Electromagnet...
Homework Statement
Two long fixed parallel wires, A and B, are 10 cm apart in air and carry 40 A and 20 A, respectively, in opposite directions. Determine the resultant field (a) on a line midway between the wires and parallel to them and (b) on a line 8.0 cm from wire A and 18 cm from wire B...
Homework Statement
Hamiltonian of charged particle in magnetic field in 2D is ##H(x,y,p_x,p_y)=\frac{(p_x-ky)^2+(p_y+kx)^2}{2m}## where ##k## and ##m## are constant parameters. For separation of this system use ##S=U(x)+W(y)+kxy+S_t(t)##. Solve Hamilton - Jacobi equation to get ##x(t), y(t)## ...
I'm trying to understand the repulsive forces of solenoids. This is all paper as in I don't actually have them to test in real life. Take two solenoids that are equal to each other.
Specifications:
current is 10 amps
Number of turns is 300
Iron rod is 12 inches/ 304.8mm, with a Radius of 2...
Hi all,
Consider one has a magnetic dipole, the field given by:
\begin{equation}
\vec{B} = \frac{\mu_0}{4\pi}\left(\frac{3(\vec{m}\cdot\vec{r})\vec{r}}{r^5}-\frac{\vec{m}}{r^3}\right)
\end{equation}
where we can take $$\vec{m} = m\hat{y}$$.
Let us say we have the a magnet vector which is...
This Science news article describes efforts to treat cocaine addiction by activating or inhibiting specific brain circuits with Transcranial Magnetic Stimulation (TMS).
TMS works by producing magnetic fields close to the scalp which in turn induce currents in different brain areas.
This can...
Homework Statement
Uploaded question(the formula in c part)
And can you tell me in which all cases that formula is used.
Homework Equations
Just want to know where the formula in c part has come from.
The Attempt at a Solution
Sum of magnetic fields due to circular plates calculated and added...
I am trying to understanding magnetism and I've been running into this thought problem
A particle a in a magnetic field B responds with Force F=|q|v x B.
frame S:
The field is B1, caused by a moving charge/s - current at speed v.
the particle is at rest, F=0.
frame S' moves with speed v/2...
Homework Statement
Homework EquationsThe Attempt at a Solution
Because of the external magnetic field ##\vec B_0 ## , a uniform magnetization will be in the direction of external magnetic field.
Because off this uniform magnetization, there will be a uniform magnetic fied in the direction of...
Hi everyone,
I have recently done an experiment testing the effect of temperature on magnetism through measurement of magnetic flux at a constant distance away from the measuring device. I used a range of 0-90 C for neodymium and bar magnets, and found a reasonably linear trend, with a similar...
If electrons have a magnetic moment (or behave like they have) why don't all orient North Up in a magnetic field (pointing down)? Plus, if thought as magnetic dipoles, like poles repel, therefore all should point the same direction. In a Stern-Gerlach apparattus shouldn't the magnetic moment...
Situation is this, consider a conductor moves perpendicular to the direction of magnetic field. But magnetic field is not uniform through out the conductor movement( but magnet is stationary and flux lines are in same direction and magic field doesn't change with time but changes with space...
1. Homework Statement
Hi. This is my first question on PF so please forgive me if something's not right
So I'm stuck at this question in EMT
In frame1, E and B are parallel and related by E=cB. We are required to find the cosine of the angle between electric field E' and magnetic field B' in...
Dear all, I know the sources of magnetic field are moving charges or varying electric field. I also know that subatomic particles(even neutron) have their own magnetic moment due to its quark and spin and their magnetic moment is explained by invoking quantum mechanics(though I don't know how...
When a magnetic field is applied across the left part of the tube , it's level rises as shown .
I would be grateful if someone could help me understand why this happens .
Thanks .
Homework Statement
To find the direction of magnetic field due to a toroid.
Homework EquationsThe Attempt at a Solution
Taking the cross - sectional shape of toroid circular, the toroid could be turned into a solenoid. A solenoid's magnetic field is along its axis. When the solenoid gets...
Homework Statement
Decide the direction of Magnetic field of a very long solenoid consisting of n turns per unit length on a cylinder with current I flowing through.
Homework EquationsThe Attempt at a Solution
Deciding direction of the magnetic field:
Considering cylindrical coordinates with...
Is it possible to have a magnetic field of a any geometry we want, or there are only few types of geometries that can be achieved with permanent magnets and electromagnets? If the former, how do we produce a magnetic field of specific geometry? For example, can the magnetic field be cylindrical...
This Wikipedia article
https://en.m.wikipedia.org/wiki/Relativistic_electromagnetism
seems (to me) imply that there is always a frame of reference in which a magnetic field can be rather viewed as an electric field modified by relativistic considerations. Is that always true? That is...
Homework Statement Homework Equations
N/A
The Attempt at a Solution
Im not sure if I've done this right because it seems too little for 6 marks. I have arrows coming from the north to the south end for the magnet's magnetic field. I have arrows going counter clockwise around the conductor...
Homework Statement
Find the magnetic field at the point distance R outside a rectangular loop of sides 2R, 4R carrying current I as shown in the attached diagram
Homework Equations
Biot-Savart Law
The Attempt at a Solution
Could I just break this up into 4 separate lines and then calculate...
Homework Statement
Consider a conductor loop which rotates about the y-axis with angular velocity w. The positive y-axis is directed into the paper, the x-axis to the right and the z-axis upwards. There is an inhomogeneous magnetic field along the positive x-axis. Calculate the magnetic flux...
How does look like electric field lines due to change of the uniform magnetic field?
Suppose we have a magnetic field between two infunite plates with surface current $i$ which is lineary change with time. Then B-filel is (x - perpendicular to plates, z and y along plates)
\begin{equation}
B_z =...
Hello all.
Me and some friends are building a coil cannon, and we've been doing some calculations [I know its unecessary but... well, we're physicists! (well, physics students...)]. But we got stuck.
How to calculate the force acting on a steel bar (or some other ferromagnetic material, maybe...
I learned this in college 48 years go, problem is I have forgotten more than I ever knew. I know the answer is not very hard like 20 degrees but the internet is pissing me off. I looked this up and I get FAKE stuff like advertisements. Novels with many pages to read that never tell the...
Consider two thin and long, single layered identical solenoids with same DC in them, positioned coaxially. I'm trying to calculate the magnetic force on each solenoid, when there are identical magnetic cores inside them.
As seen in below, I have the general approximation to the force between...
Homework Statement
Homework EquationsThe Attempt at a Solution
using the left hand rule, second finger points the direction of current, thumb points direction of motion and first finger the direction of magnetic field. But If direction of current and motion is the same, what do I do? Thanks~
Homework Statement
A rectangular loop of wire, L = 28.8 cm and W = 15.2 cm, carries a I1 = 2.02 A current and lies in a plane (d = 11.0 cm), which also contains a very long straight wire carrying a I2 = 12.7 A current as shown in the figure below.
Homework Equations
F=uo*i1*i2*l/perpindicular...
(1) Magnetic force acting on charge moving in magnetic field is given by,
F = qvBsinθ...F ∝ v
This means that if moving charge particle has more velocity then more magnetic force will act on it.
Due to more magnetic force the direction of velocity changes rapidly and it will move on the...
Homework Statement
Homework EquationsThe Attempt at a Solution
I know if the currents are going the same direction they attract. So the top 2 attract each other and the bottom two attraction each other? And then the top repel the bottom...
I'm stuck, please help~
Homework Statement
Homework EquationsThe Attempt at a Solution
Shouldn't they be the same? Does one being above the current and the other being below make any difference? I know when there is a higher density of magnetic field lines, the magnetic field strength is greater, but in this case...
Homework Statement
What is the force on an electron with a velocity v = (2i – 3j) Mms-1 in a magnetic field B = (0.8i +
0.6j – 0.4k) T
Homework Equations
F=qvBsinθ
The Attempt at a Solution
using cross product I got: (1.92i + 1.28j + 5.77k)10^-13 N which is the listed correct answer.
My...
so i am literally one step away from producing a floating skateboard powered by permanent magnets,
so here's what i wanted to check, to make sure I haven't missed anything obvious
vertical lift achieved by using vertical repelling fields
rotational motion is controlled by counterbalancing the...
Hi,
I can't find my inductance calculations book. Say that you were considering magnetic flux linkage more from a geometric perspective:
-Does the mutual coupling coefficient for a series of coils all on the same steel core add up to a maximum total of ~1?
Because I tried simulating a three...
Homework Statement
Two wires with the same intensity but with opposite directions.
The magnetic field of the middle line between the two wires is:
a) (X)
b) (o)
c) Parallel between the two wires
d) Null
e) Non of the above.
Homework Equations
N/A
The Attempt at a Solution
Knowing that they...