Tagged Questions
0
votes
0answers
27 views
Energy or Work done to pull an Iron cyclinder into a Solenoid
RadiI have been following the calcuations from these lecture slides here (slide 11). Where the slides attempt to approximate how much a solenoid pulls, by working out the energy required to pull an ...
0
votes
1answer
80 views
Energy stored in fields
How to intuitively think of energy stored in a magnetic/electric field?
Kindly answer in a bit simple terms without referring to mathematics.
-1
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2answers
227 views
Why perpetual motion wouldn't be possible if we are so technological advanced?
Why perpetual motion wouldn't be possible if we are so technological advanced?
It is just a thing that I was wondering for too long. I mean, we are able to create so powerful permanent magnets, like ...
8
votes
3answers
321 views
Where's the energy in a boosted capacitor?
Suppose I look at a parallel plate capacitor in its rest frame and calculate the electrostatic energy, $E$.
Next, I look at the same capacitor in a primed frame boosted in the direction perpendicular ...
3
votes
2answers
120 views
Why is there a factor of 1/2 in the interaction energy of an induced dipole with the field that induces it?
In this paper, there's the following sentence:
...and the factor 1/2 takes into account that the dipole moment is an induced, not a permanent one.
Without any further explanation. I looked ...
1
vote
2answers
505 views
Conservation of Energy in a magnet
When a permanent magnet attracts some object, lets say a steel ball, energy is converted into for instance kinetic energy and heat when attraction happens, and they eventually collide. Does this imply ...
1
vote
3answers
237 views
Extract energy from magnets
Is it possible to "extract" energy from a magnet, making it lose its magnetism? Or, to put in another way, is magnetism a form of energy? (I am not talking about potential energy in a magnetic field). ...
0
votes
1answer
173 views
Faraday's law and superconductivity
According to Faraday's law of induction, volts = -Number of coils in a solenoid * change in strength of magnet / change in time. This doesn't take into account distance or speed, only time. If amps = ...
3
votes
2answers
337 views
Energy in an EM wave should depend on frequency
I just finished reading Feynman's Lectures on Physics vol.I, ยง34-9: "The momentum of light". The author explains that there is a relation between the wave 4-vector $k^{\mu}$ and the energy-momentum ...
0
votes
1answer
160 views
Violation of conservation of energy and potential energy between objects
I would like to clarify my question. I have numbered them to be independent questions
For any conservative fields, $\vec{F} = -\nabla U$. Which means the restoring force is opposite to the ...
3
votes
1answer
322 views
Is there something like the Poynting vector for hydraulic circuits?
The Poynting vector is a representation of the energy flux in electromagnetics, showing the amount and direction of power flow at different points in space. In electric circuits, the energy is not ...
1
vote
2answers
585 views
If electric charges accelerate towards lower potential energies, why do opposite charges attract?
I know my logic must be wrong but I can't figure out why. I know that charges must accelerate towards lower potential energies simply because that's a general rule of nature. However, when you release ...
2
votes
2answers
341 views
Does space have to be filled with charged particles to carry electromagnetic waves?
I'm a newbie here so have mercy.
I'm studying electromagnetic waves. This is the propagation of energy via the vibration of charged particles, as I understand it.
A charged particle could be like ...
1
vote
1answer
124 views
The energy carried from one winding of a transformer to another, in quantum terms
I have read in wikipedia this statement
"The energy carried from one winding of a transformer to another, in quantum terms is carried by virtual photons, not real photons" (wikipedia src: virtual ...
9
votes
4answers
489 views
fraction of magnetic energy stored outside a solenoid
If I have a long solenoid, e.g. length $l$ and radius $r$ with $l = kr$, where k >> 1, with a nonpermeable (e.g. air) core, how much of the magnetic energy is stored outside as compared to inside?
If ...
2
votes
4answers
1k views
Can heat be transfered via magnetic field in a vacuum?
Say you want to store hot coffee in a container surrounded by a vacuum. To remove all sources of conductive energy loss the container is suspended in the vacuum by a magnetic field and does not have a ...
0
votes
1answer
185 views
My computer turns on when it “sees” me [closed]
Before asking, I swear that, for how it may seem strange, this is all true. Very briefly, when my pc is off and I am near it, it turns on. I do not touch anything. Nobody else have the same effect. I ...
6
votes
2answers
367 views
1
vote
3answers
498 views
Does the energy of a magnetic field decrease when it moves a conductor carrying a current?
When a charged particle moves in an electric field, the field performs work on the particle. Thus, the energy of the field decreases, turning into kinetic energy of the particle.
Does the magnetic ...
