All Questions
26
questions
1
vote
1
answer
65
views
Potential energy of a permanent magnet
A friend and I had a discussion about the potential energy of a permanent magnet, and we want to find out which of our views is right, but we can't seem to find information to confirm/disprove either ...
- 11
0
votes
1
answer
83
views
The magnetic force is conservative when the magnetic field is static, what is its potential function then?
The magnetic force $\vec{F}$ can be conservative when the magnetic field is a static. That is $\vec{\nabla} \times \vec{F}=0$, so it follows that there is a scalar function $f$ such that $\vec{F}=q \...
- 959
2
votes
1
answer
91
views
How to calculate magnetic force using differentiation of magnetic energy?
I tried to calculate the magnetic force between two circular current loops using numeric integration and differentiation of magnetic energy:
$$ \int d^3\vec{r} \frac{1}{2 \mu_0} \vec{B}^2 \,\,\,\,\,\,...
- 425
0
votes
1
answer
124
views
Violation of energy conservation due to Lorentz Force?
We know that work done by Lorentz Force $q(\vec{v}\times\vec{B})$ is $0$ on moving charge in magnetic field as velocity is always perpendicular to the force. This means that kinetic energy remains ...
- 1,168
3
votes
2
answers
636
views
How can we define Magnetic Potential Energy if it is non-conservative?
I recently learnt that for a circular wire carrying electric current or for a magnetic dipole, if it is kept in a uniform magnetic field, we can define its magnetic potential energy. This would mean ...
- 301
2
votes
1
answer
120
views
When creating a magnetic field with a coil in the vicinity of a static magnet, where does the potential energy of the magnet come from?
Imagine I have a coil/solenoid with an iron core, just a typical eletromagnet. A rod magnet is located at some distance to it. Imagine they are positioned and oriented like this:
...
- 124
4
votes
1
answer
818
views
Two permanent magnets are allowed to attract each other. The field energy MUST decrease as they speed up. But Griffiths implies it INCREASES. How?
This is a relatively long question however I think I hit on a fundamental issue regarding the conservation of energy during magnetic attraction and how it is taught in standard texts. I'd really ...
- 1,581
1
vote
4
answers
517
views
Can non-conservative fields store potential energy?
I was taught that a time-varying magnetic field generates an electric field which is non-conservative in nature, and my teacher also told me that when a conducting coil is placed in a region with a ...
- 8,230
2
votes
1
answer
83
views
How do I find the potential energy lost by a ball bearing moving away from a magnet?
I am carrying out a physics project over the next few weeks and am looking at the Gaussian gun. I'm sure most are familiar with it, but if not it is the experiment where you roll a ball bearing into ...
- 21
1
vote
0
answers
44
views
What's the potential energy in a system of magnets?
I am trying to model a 3d pendulum consisting of a magnetic bob attached to a string. If the pendulum is allowed to swing over a structure of permanent magnets, it will display complex motion (here a ...
- 91
2
votes
1
answer
409
views
What is doing the work on a magnetic dipole in a magnetic field?
I understand that the torque acting on a magnetic dipole in a magnetic field is given by $$\vec\tau=\vec\mu\times\vec B \therefore \tau = \mu B sin\phi$$ It follows that the work done as the dipole ...
- 155
1
vote
2
answers
534
views
Source of magnetic dipole potential energy
One of the basic expression that goes without much thinking is the potential energy expression of a magnetic dipole in a magnetic field, $$ U = -\mu\cdot B $$
In the case of electric and gravitational ...
1
vote
3
answers
206
views
How energy stored in magnetic field gets used up?
An inductor stores energy in form of magnetic field. In case of capacitors the energy is stored in electric field, and since electric field can do work the stored energy can be spent. Here, magnetic ...
- 662
1
vote
0
answers
27
views
How can I find the potential energy and force between a steel sphere and a magnet?
I'm fine with certain simplifying assumptions being made, I currently only know high-school level physics (the simpler the better). Also, if anyone can explain the intuition behind formulae, I would ...
35
votes
5
answers
6k
views
Why don't we define potential due to a magnetic field?
We define electric potential and gravitational potential and use them quite often to solve problems and explain stuff. But I have never encountered magnetic potential, neither during my study (I am a ...
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