All Questions
13
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What is the physical meaning of the torque term involving the magnetic displacement force?
In Zangwill's Modern Electrodynamics the magnetic torque is derived in Eq. 12.63 to be
\begin{equation}
\mathbf{N}(\mathbf{r}_0) = \mathbf{m} \times \mathbf{B}(\mathbf{r}_0) + \mathbf{r}_0 \times \...
2
votes
1
answer
113
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Why can we calculate force on a dipole from torque?
In the Feynman lectures he derives the (mechanical) energy of a dipole
$$ U = -\boldsymbol{\mu}\cdot \boldsymbol{B} + \mathrm{constant}$$
by considering only the torque on it in a uniform field. He ...
- 2,122
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2
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39
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How great is the net force exerted on a superconducting material of a small size being subjected to an external uniform magnetic field?
Assume that we have a very tiny spherical or disk-like superconducting material that is subjected to an externally uniform magnetic field. I want to know if the net force that accelerates the ...
- 2,503
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26
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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
240
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What direction does magnetic dipole moment feel force in parallel magnetic field?
Suppose I have a magnetic dipole oriented vertically in the $\hat{z}$ direction so
$$ \vec{m} = m\hat{z}$$
And the position vector to it is $\vec{r} = z\hat{z}$. It's entirely on the z-axis.
We're ...
0
votes
1
answer
160
views
Tesla to Newtons Over Given Distance
I have a Neodymium magnet, for example, that has a magnetic flux density of $1.25 \;\text{T}$ and is 1 inch by 1 inch by 0.44 inches. I have a steel ball with a diameter of 0.5 inches placed 3 inches ...
1
vote
2
answers
273
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Magnetic dipole moment because of spinning electron
We always consider only the spin of electron. But protons are spinning charges as well. So what about the magnetic dipole moment caused by them?
- 453
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1
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2k
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What is $dB/dx$ where $B$ is magnetic field and $x$ is the separation between two magnetic dipoles?
I came across a question regarding the force between two magnetic dipoles $M_1$ and $M_2$ separated by a distance $x$ .
Here in this text book I am given the solution is
$$ B = \cfrac{\mu_0}{4 \pi}...
- 29
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votes
1
answer
190
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Why is there no B-field parallel force on an electron orbiting a magnetic field line?
If an orbiting electron creates a toroidal magnetic field like a ring of current does, and this field is oriented opposite to the magnetic field line the electron is orbiting, then why is the electron ...
- 3
2
votes
1
answer
362
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Current Loops VS Permanent Magnets
I'm having a hard time understanding the big connection between permanent magnets and current loops. I am aware that they both have the same magnetic field and therefore it can be said that a current ...
- 81
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136
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Is there a mistake in these two equations describing force between magnetic dipoles?
The first equation appears here. (Force between magnets#Magnetic dipole-dipole interaction on Wikipedia)
$$\mathbf{F}(\mathbf{r},\mathbf{m_1}, \mathbf{m_2}) = \frac{3\mu_0}{4\pi r^5} \left[(\mathbf{...
- 1,386
0
votes
2
answers
331
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Atomic orbit in a magnetic field and sign conventions
Kindly refer to page 261 in the link below:
Click here
Griffiths claims that for an electron orbiting an origin, the centripetal acceleration is sustained by the electrical forces
$\frac{1}{4 \pi \...
- 889
3
votes
2
answers
735
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Contradicting forces on a circular loop under current in magnetic field?
I have the following general conceptual concern.
Think of a thin conducting loop of radius $R$ placed in the $x$-$y$-plane at $z=0$. There is a homogeneous current density $\vec{j}$ running through ...
- 1,517