The discussion centers around whether light can create an electromagnetic field and the implications of this for electromagnetic induction. Participants explore the nature of light as an electromagnetic wave, its interaction with conductors, and the conditions under which it may induce current.
Participants express differing views on the ability of light to induce current and the reasons behind the limitations of electron movement in conductors. There is no clear consensus on these points, and the discussion remains unresolved.
Participants reference the high frequency of light as a key factor in its interaction with conductors, suggesting that this frequency affects the ability of electrons to respond. The discussion includes various analogies and explanations, but no definitive mathematical or physical conclusions are reached.
Is it field?Danger said:Light is an electromagnetic field. It is simply our way of identifying the visible (and near-visible) segment of the EM spectrum. There are several arbitrarily defined segments such as microwave, radio, X-ray, gamma, IR, etc.. Light is generally considered to be the part that we can see.
Yes. There is one and only one difference between, say, and EM wave at microwave frequencies and that of a red beam of light is the frequency of the waves. They are exactly the same in physical properties and makeup.scientist91 said:Is it field?
pmb_phy said:Yes. There is one and only one difference between, say, and EM wave at microwave frequencies and that of a red beam of light...
scientist91 said:If you say that the light is field, then I will make electromagnetic induction with light and get current in closed circular loop.
Can you give me some link or picture?ZapperZ said:And you do! People who work in designing accelerator cavities have to deal with wall currents due to the the changing B fields. That is why you have lossy material.
Zz.
scientist91 said:Can you give me some link or picture?
So let's conclude the light is electric and magnetic field, right?
Due to the high frequency of a light wave the light would not be able to penetrate inside a conductor. Same thing with x-rays.scientist91 said:If you say that the light is field, then I will make electromagnetic induction with light and get current in closed circular loop.
Look man, if you say that the light is both part of magnetic and electric field, then, the photons "are moving" (so the magnetic field is moving), so it will produce current inside the conductor, right?pmb_phy said:Due to the high frequency of a light wave the light would not be able to penetrate inside a conductor. Same thing with x-rays.
You wanted a picture, right? Draw a picture of an EM wave and you have by neccesity drawn a picture of light.
What part of "Light is an EM wave" don't you understand?? Its a pretty simple idea.
Pete
scientist91 said:Look man, if you say that the light is both part of magnetic and electric field, then, the photons "are moving" (so the magnetic field is moving), so it will produce current inside the conductor, right?
Why the electrons can't move so fast when the magnetic field of the light is moving so fast? Practically, when you move magnetic field faster, so the electrons in the conductor are moving faster, so the current is stronger.Xezlec said:It does produce a current. YES. Light does produce an electric current in any conductor it hits. Indeed.
But light has a very high frequency. So because the frequency is so high, the "electrons in the conductor can't move fast enough". So the current is very very very very small.
That's an oversimplification, but I don't know what else to say that will be understood.
scientist91 said:Why the electrons can't move so fast when the magnetic field of the light is moving so fast? Practically, when you move magnetic field faster, so the electrons in the conductor are moving faster, so the current is stronger.
Suppose you are pushing a child in a swing. Let's say you give a push every two seconds, to increase its amplitude. What would happen if you gave a push every tenth of second? The swing wouldn't move much. Make the experiment.scientist91 said:Why the electrons can't move so fast when the magnetic field of the light is moving so fast? Practically, when you move magnetic field faster, so the electrons in the conductor are moving faster, so the current is stronger.
I think you have wrong understood it. Look, I made that experiment. So if I push with 0.1sec (with same power) when I will get to 2 sec (0.1*20) so the swing's moving speed will be so fast, 20 times more then once in 2 seconds.lightarrow said:Suppose you are pushing a child in a swing. Let's say you give a push every two seconds, to increase its amplitude. What would happen if you gave a push every tenth of second? The swing wouldn't move much. Make the experiment.
But man, when you practically moving magnet among conductor, it will induce current inside of the conductor. When you move the magnet very fast so the electrons are moving very fast, right?Xezlec said:It's hard to explain in such simple language. Pick up a spring. Hold it by one end. Move it up and down slowly. Now try moving it faster, and faster, and faster. Eventually the spring won't bounce very much anymore because you're shaking it too fast. It can't keep up.
Electrons have mass, and they also have other things "holding" them. They are stuck in a "soup" of other electrons, so they can't just move as fast as you want.
scientist91 said:But man, when you practically moving magnet among conductor, it will induce current inside of the conductor. When you move the magnet very fast so the electrons are moving very fast, right?
scientist91 said:So, when you move the magnet very fast among conductor in closed circular loop you create stronger current. But what will happen if the light wave oscillate hundrets of trilions times per second? The electrons will not move, but why?
Can understand what actually happens with the electrons. They must move when there is presence of magnetic field, so when you move the magnet very frequently you get current, still I can't understand, what actually happens when there is presence of light with high frequency.rbj said:you're not listening. whether you are generating light (or any other E&M field) or receiving such a 'transmission", electrons (or some other charged object) are, at least in a probabilistic sense, moving back and forth. even at trillions of Hz. eventually frequencies get so high that matter doesn't have much ability to deal with it. i think your DNA would get messed up if you were exposed to enough gamma or cosmic radiation.
but 91, you just need to accept that visible light is just another set of frequencies in the broad EM spectrum. that's what several other people are trying to confirm to you.
As we are trying to make you understand (I tried with the example of the swing but I had no success!), since electrons have a non-zero mass and so have inertia, if you try to move them with an oscillating force which frequency is too high, they cannot follow the movement of the force; just because of their inertia, at the time they have started moving in one direction, the force has already changed direction, so they don't have time to follow its movement. Try to figure it out.scientist91 said:Can understand what actually happens with the electrons. They must move when there is presence of magnetic field, so when you move the magnet very frequently you get current, still I can't understand, what actually happens when there is presence of light with high frequency.
Ok now I understood it, but I have one more question, are the electrons moving in conductor (with current), moving like they move in nuclei (spinning)? When they are excited and gain energy and unbound from the atom, they release the excess of energy?lightarrow said:As we are trying to make you understand (I tried with the example of the swing but I had no success!), since electrons have a non-zero mass and so have inertia, if you try to move them with an oscillating force which frequency is too high, they cannot follow the movement of the force; just because of their inertia, at the time they have started moving in one direction, the force has already changed direction, so they don't have time to follow its movement. Try to figure it out.
But notice, you would have the same exact situation with every object with non zero mass, accelerated with a force with constant amplitude but increasing frequency: in the simpler case of a free object, the amplitude of its oscillations decreases as the force's frequency increases.
When they are excited and gain energy and unbound from the atom, they release the excess of energy?
Sojourner01 said:No. For a start, you've got this muddled:
Electrons in atoms release energy when they drop through energy levels. They absorb energy to gain energy levels, and eventually dissociate entirely.
Even so, this isn't what happens in a conductor. Electrons in metals move as though they are free, even though they are in fact still in the potential of the nuclei. This property is what makes metals metallic; this is what metallicity is. The mechanics of this are complicated and I don't fully understand them myself, suffice to say it's to do with the periodic nature of the nuclear potential wells.