All Questions
27
questions
0
votes
0
answers
20
views
How to find permeability of a magnetic material?
I have been working with magnetic materials for quite some time now and never really explored this fundamental parameter. After looking through the literature I realize there and quite few different ...
- 11
0
votes
1
answer
35
views
Internally, what defines whether a material is magnetically hard or soft?
I know that magnetically hard materials hold magnetic fields (magnetic moment alignment) for longer, while soft metals do not. However, what, internally, causes these properties to arise?
- 185
0
votes
2
answers
42
views
Magnetization current when two magnets are brought together and the Lorentz force law
Suppose we have two ferromagnetic objects constituting two permanent magnets. A classical way to think of the two magnets repelling/attracting each other would be by ascribing bulk and surface ...
- 8,640
1
vote
0
answers
11
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Is there any way to detect localized magnetic field change in a magnetic material or powdered magnetic material?
Hi I was wondering if there was any way to detect localized magnetic field change within either bulk magnetic material or within like powdered magnetic material. The application we are looking for is ...
- 11
0
votes
1
answer
327
views
What will happen if I pass Current through Permanent bar Magnet?
Following the Picture below,
If I Conduct current through Permanent magnet Bar and hold the battery still. Will the magnet move in any direction ? Thank you.
- 21
2
votes
0
answers
30
views
How to calculate the Force between a magnet & an induced dipole? [closed]
https://www.youtube.com/watch?v=xTwDZJG_W9w
In this video at 9:12 it details the potential energy of an induced dipole
Specifically
$$U=-mBcos\theta=(\frac{\chi V}{\mu_0}B)Bcos\theta$$
&
$$F_z=\...
- 87
2
votes
2
answers
167
views
Energy Conservation when two permanent magnets attract each other
I have a very basic doubt related to energy conservation in a system of magnets. Suppose I have two magnets (bar magnets) of magnetic moment $M$ kept along the line with an initial distance $X_0$ such ...
- 31
1
vote
2
answers
132
views
How Mars have so less magnetic field if it spins?
Moving charges have magnetic fields. If Mars spins, it moves and so the core with it and so will the electrons inside it. Then why it needs liquid core to have strong magnetic field, what about the ...
- 21
0
votes
2
answers
172
views
Why armature is being rotated in DC generator?
I am wondering about why armatures are being rotated instead of being static?
The magnetic flux will still cut the armature windings and because of this induced current will be generated.
So, why it ...
1
vote
1
answer
91
views
How to reduce magnetic field between two magnetic shield sheets (silicon steel sheets)?
I put 2 parallel silicon steel sheets between magnetic field as below:
As silicon steel has much bigger permeability than air,magnetic line will go through 2 silicon steel sheets.
What I can do to ...
- 127
0
votes
2
answers
762
views
How can I find the force of a solenoid with a moving plunger?
It seems like it should be a simple equation, until I realized that the core isn't magnetized until it is induced, then there is a dipole moment, and then as it moves the core of the solenoid ...
- 103
2
votes
0
answers
24
views
How many electrons in a ferromagnetic material, per atom, have their spins pointing in the same direction?
Is there a list or chart somewhere that states, approximately, how many outer electrons per atom in a particular ferromagnetic material are aligned?
Are there, say, five electrons in an FeO2 magnet's ...
- 4,509
1
vote
3
answers
1k
views
How to mathematically show that magnetic field in Helmholtz coil is homogeneous
From the title of the question you have probably already figured out what my question is...
How to mathematically show that magnetic field in Helmholtz coil is homogeneous?
I know that magnetic field ...
0
votes
2
answers
101
views
Does a straight, current-carrying wire always repel a permanent magnet? Regardless of the permanent magnet's orientation?
Several people have told me that a current-carrying wire usually (or always) repels a nearby permanent magnet....
Most recently, I saw this Veritasium video on YouTube: 'How Special Relativity Makes ...
- 4,509
0
votes
1
answer
242
views
Ampere's law: the position of amperian loop
Can Amperian loop be taken parallel to current. I.e suppose current is in a circular loop in xy plane. And let the screen you are watching is xy plane . Can we take amperian loop in the same plane.
...
- 95
1
vote
0
answers
27
views
Relation between drift velocity and area velocity
Is there any relation between drift velocity and area velocity?
And how I can to find area velocity for electrons in a magnetic field?
- 31
2
votes
0
answers
428
views
Energy of Magnetic Dipole
What is the total energy of a magnetic dipole, $\textbf{m}$, in the presence of a magnetic field $\textbf{H}_s$?
I've seen the typical answer given is:
$U = - \textbf{m}.\textbf{B}\Delta_v + U_s$
...
- 21
0
votes
1
answer
42
views
Drone's sufficient engine RPMs initiated by Magnetic Fields
I've seen many videos where magnets are used to initiate and boost RPMs. Most of them are fake, where people are using compressed air at the backstage.
Did anyone of you actually tried to challenge ...
- 1
1
vote
2
answers
148
views
How can diamagnetism levitate anything?
From the explanation of diamagnetism that I was given, the electrons when exposed to a changing magnetic field will change their spin in accordance to Lenz's law. This will induce an opposing magnetic ...
- 2,356
0
votes
1
answer
77
views
Confusion regarding torque given by M×B
The magnetic torque acting on a loop of magnetic moment M placed in a magnetic field B, is given by τ=M×B.
My question is, about which axis does this give the torque about?
Is it the instantaneous ...
- 257
3
votes
1
answer
539
views
Can $F=qvB$ be applied to a solenoid and a parallel moving magnet?
If you take a scenario like this,
Charge gathers at either end, and if you could somehow form a complete circuit without there being a canceling effect, there would be a current flowing. This makes ...
- 347
-2
votes
2
answers
307
views
Does the magnetic field line passing along the axis of a bar magnet ever reaches to South Pole?
Consider a bar magnet, and the magnetic field line that goes through its axis and through the center of its north pole and thus follows a straight line path out of the magnet. Will this line ever be ...
0
votes
1
answer
49
views
Can magnetic resonant inductive coupling work in magnetic resonance (specifically in NMR and MRI)?
Radiofrequencies are usually used to flip polarized nuclei in a magnetic field in NMR and MRI. These RF correspond to the Larmor frequency of those nuclei.
Since the effect from the RF is usually due ...
3
votes
1
answer
461
views
Lenz' law and magnetic moment
Lenz Law says that the induced current will circulate in a direction such that it produces a magnetic field that is opposite to the change of applied magnetic field. For example, if the loop is a ...
- 890
0
votes
2
answers
1k
views
Magnetic Force of a current carrying wire loop on a magnetic object
let's say we have a current carrying wire loop WITHOUT AN EXTERNAL MAGNETIC FIELD. It produces a magnetic field on its own. what would the magnetic field and force of this loop on a charge or a ...
1
vote
2
answers
891
views
Spinning charged sphere, magnetic energy
I have a question about this task:
Consider a thin spherical shell of dielectric which has a radius R and rotates with an angular welocity $\omega$. Suppose that the mass of the shell is negligible.
...
- 789
0
votes
3
answers
624
views
Deflection of compass and rest position through Magnetic induction
I found a problem with a compass and a magnet, as diagrammed below.
The needle of the compass was oscillating in an uniform magnetic field, but when a soft iron bar was placed near the needle, then ...
- 333