2
votes
1answer
38 views

The Energy involved in the work done here?

When a wire that has current $I$ flowing within it and its in a magnetic field, the wire experience the Lorentz force, and that force moved the wire over a certain distance $x$(no matter how small), ...
1
vote
1answer
72 views

Is magnetic wheel possible?

I once tried to make a magnetic wheel using different shaped magnets and placing them in different orientations and of different shapes.But it did rotate making a small angle ie it didnt rotate even a ...
1
vote
1answer
79 views

The relation between the movement of electrons and energy

So, I've been enjoying reading a lot of helpful posts, but now, I found myself in the need of asking something. I have a hard time grasping the general concept of electricity / how the relation ...
0
votes
1answer
35 views

How does electric current generate thermal energy?

How does free electrons moving through a wire cause random vibrational motion of the positive ions?
4
votes
1answer
86 views

How does a flywheel generate electricity at a constant voltage?

I believe I am missing something simple here. My question concerns flywheel energy storage. Say we have stored some amount of energy in a spinning flywheel. The flywheel is attached to a generator. ...
0
votes
0answers
18 views

Energy due to polarization opposing dipoles from alignment

Can polarization produce heat? If so will this energy oppose dipoles aligning in the field direction?
1
vote
3answers
182 views

Is a real life electric shield possible? [closed]

I got this question from playing games like Halo and Borderlands (I know kinda dumb but raised a good question) in which the primary protection is an electric shield. Now I'm wondering if it would be ...
0
votes
0answers
40 views

Which is more energy efficient: optical demagnetization or heating beyond $T_c$,

What is considered more energy efficient? Current research show that the amount of energy used for powering a laser to demagnetize a material is quite small. However, the demagnetization is very ...
-1
votes
2answers
85 views

Time difference in transmission of AC and DC

Is there any time difference while considering the transmission of AC and DC ? Is either one of them faster than the other one in terms of transmission of energy/power from one point to another? I ...
0
votes
0answers
44 views

Energy required to demagnetize a soft iron?

How much energy is required to demagnetize a soft iron ferromagnetic material, that has a very low coercive force And a small hysteresis area? Also, would it be possible to demagnetize that same ...
3
votes
2answers
294 views

Energy density in Magnetic fields?

I don't understand what does magnetic field energy density stand for? The possible work that the magnetic field can do? So we can calculate the amount of "work" it can do just from the energy density? ...
0
votes
2answers
343 views

How do I express the interaction energy between two charged spheres?

Consider two identical insulating spheres each with radius $R$ and uniform charge $Q$ through their volume. They are separated from their centers by a distance of $d>2R$. Here is my general ...
3
votes
2answers
151 views

Moving the plates of a charged capacitor to calculate energy density - where's the flaw in my argument?

For a charged air-dielectric capacitor, let the plates be parallel to the $xy$ plane, with the top carrying a positive charge $+Q$, the bottom a charge $-Q$. The force on an infinitesimal charge ...
0
votes
1answer
57 views

Energy spent by motor in a period

Consider a single coil that is turning in a constant and uniform magnetic field thanks to a motor. The normal to the coil is given by: $${\bf u}(t)=\sin (\omega t){\bf u_x}+\cos(\omega t){\bf u_z}$$ ...
2
votes
1answer
196 views

A dielectric table is being inserted between a plate capacitor and $\triangle U<0$ how to deduce the table is attracted to the plates?

I am practicing for an exam in my Physics $2$ course. One of a previews exam questions described a plate capacitor and asked to calculate the initial energy $U_{0}$, then a dielectric table was ...
1
vote
0answers
40 views

what are the main factors holding back magnetic energy storage systems?

Perhaps is it the magnet's own magnetic field that causes it to lose its superconductive state? It seems as though these systems could become incredible energy dense.
0
votes
2answers
465 views

How to transform mechanical work into electrical energy without using piezoelectricity?

can someone help me with the following issue. I need a method for transforming mechanical work into electrical energy without using piezoelectricity. I have such kind of mechanical forces (like on the ...
2
votes
2answers
232 views

Energy of electron spinning in a magnetic field

When an electron travels in circles in a uniform magnetic field, it must lose energy because all accelerated charges radiate, and must therefore spiral down to the center. Is this energy compensated ...
2
votes
2answers
181 views

Coincidence, purposeful definition, or something else in formulas for energy

In the small amount of physics that I have learned thus far, there seems to be a (possibly superficial pattern) that I have been wondering about. The formula for the kinetic energy of a moving ...
5
votes
3answers
363 views

Does a magnet contain (and potentially produce) energy?

Very quick question, does a magnet contain energy? The general consensus seems to be, it does not. And this is generally confirmed by the fact that it would break the first law of thermodynamics. ...
0
votes
1answer
169 views

does matter radiate energy? [duplicate]

Since we know that all accelerated charges radiate energy and we also know that all matter is made up of protons and electrons which are all the while doing accelerated motion.So from this can i ...
0
votes
1answer
213 views

From where do the permanent magnets get energy from? [duplicate]

I have a doubt about permanent magnets. If a magnet is permanent it can attract some materials permanently. Attracting something involves energy. If a permanent magnet can do this forever, from where ...
0
votes
0answers
84 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
133 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.
0
votes
2answers
317 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
410 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 ...
4
votes
2answers
382 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
1k 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
428 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
271 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
796 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
190 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
421 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
1k 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
726 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
142 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
617 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
2k 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
192 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
391 views

Using energy from sun magnetic field

Knowing ...
2
votes
3answers
729 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 ...