All Questions
22
questions
1
vote
1
answer
36
views
Magnetic moment of a paramagnetic cylinder
I am currently struggling with a problem where I have to calculate the magnetic moment $M$ of a
cylinder of radius $R$ and height $h$ made up of a paramagnetic material (aluminium) and under a ...
- 13
0
votes
1
answer
234
views
How does the Lagrangian work with a magnetic field?
I was told the following Lagrangian is for a charged particle with spin moving in a constant magnetic field:
$$
L = \frac{\left ( \vec p \right ) ^2}{2m} + \vec \mu \cdot \vec B$$
Let's just say $B$ ...
- 59
0
votes
0
answers
26
views
Where does force act in two parallel current carrying conductors?
F=ILB.so consider length as 5 m and I as 2 ampere and B as 5 T.so the force is 50 N.does this 50 N act at one point or equally applied on full length like pressure.So what does force/length in this ...
- 1
1
vote
1
answer
66
views
Magnetic dipole moment due to folded loop [closed]
A steady current i flows in a small square loop of wire of side L in a horizontal plane. The loop is now folded about its middle such that half of it lies in a vertical plane. Let
$
μ_1
$
and
$
μ_2
$
...
- 15
0
votes
1
answer
2k
views
Deriving the magnetic field due to a dipole
I am trying to follow along with a derivation from Cullity, Introduction to magnetic materials 2011. I am getting stuck at a very early stage when computing the components of the magnetic field at a ...
0
votes
1
answer
488
views
Griffiths E&M questions about example 6.1 [closed]
I understand why $K_b = M\mbox{sin}\theta \hat{\phi}$ but when I try to use this to calculate the magnetic field, I keep coming up with an integral that cancels itself out and I don't understand how ...
- 324
3
votes
1
answer
731
views
When can we use Ampère's Law methods to find $\mathbf{H}$ field?
I was reading David J. Griffiths Introduction to Electrodynamics and came across this question today.
Part (b) of the question can be solved by realising that $\mathbf{H}$ (the auxiliary field), by ...
- 323
0
votes
1
answer
502
views
Magnetization of a cylinder
Suppose we have a short circular cylinder of radius $a$ and length $L$ carrying a uniform frozen-in’ magnetization $\mathbf{M}$ parallel to its axis.
Why is there no bound surface current on the two ...
- 78
0
votes
1
answer
85
views
2 magnet bars are placed in same plane and one of them can rotate freely. The relation as system is balanced [closed]
Each magnet is in same plane.
$$ \ell \ll r $$
The magnet1 has been fixed.
The magnet2 can rotate with center of the magnet itself.
$$ \theta_{1} ~~,~~ \theta_{2} :=\text{each angle between the ...
0
votes
1
answer
96
views
Does the magnetic field exert a force on the magnetization current inside the ferromagnet?
Does the magnetic field exert a force on the magnetization current inside the ferromagnet?
In this case, does the following formula also apply?
$$
\pmb {d \hat F = I_{m} \ d \hat{L} \times \hat{B}} \...
- 11
0
votes
0
answers
72
views
What is the total momentum of EM fields?
I have an assignment where i have to find the total momentum of an EM field. Imagine a perfect magnetic dipole in (0,0,0) with dipole moment $$ \mathbf{m} = m\mathbf{\hat{z}} $$
And also a point ...
- 101
1
vote
2
answers
331
views
How to calculate pole strength for this magnet?
I know magnetic mono poles don't exists and a magnetic poles always have equal strength. But what about a magnet which looks like this?
This is picture of magnet whose thickness is constantly ...
- 1,691
0
votes
2
answers
57
views
Magnetic moment of a radially symmetric current
In my latest assignment I'm tasked with finding a magnetic moment $\mu$ of a hydrogen atom, whose current distribution $\mathbf{j}(\mathbf{r})$ looks like
$$\mathbf{j}(\mathbf{r})=\frac{e\hbar}{3^8 \...
4
votes
1
answer
415
views
Magnetization currents (amperian currents): how to show that they are always zero in total from the definition?
For magnetic field in matter the two following amperian current densities are defined:
Surface currents: u.m. $[\frac{A}{m}]$
$$J_{A,s}= \bf{M} \times \hat{n}$$
Volume currents: u.m. $[\frac{A}{m^...
- 2,617
1
vote
1
answer
1k
views
Work on current loop placed in a magnetic field: how can there be work done against magnetic forces? [duplicate]
I'm facing some doubts while studying the lecture on magnetic dipole potential energy http://www.feynmanlectures.caltech.edu/II_15.html - "15–1 The forces
on a current loop; energy of a dipole".
When ...
- 2,617