I read that the source of all light/EM radiation is an electron being energized to a higher orbit, then falling back and shedding a photon. But, I also read that an antenna transmits radio by dint of the e's in the antenna being vibrated back and forth so that the electric field lines emanating from them wiggle, like shaking a rope at one end and making waves travel down the rope, and these waves, with the help of their magnetic fields, propagate through space. Is that also an instance of e's rising and then falling? Many thanks.
DaveC426913
Jul4-08, 01:58 PM
I read that the source of all light/EM radiation is an electron being energized to a higher orbit, then falling back and shedding a photon. But, I also read that an antenna transmits radio by dint of the e's in the antenna being vibrated back and forth so that the electric field lines emanating from them wiggle, like shaking a rope at one end and making waves travel down the rope, and these waves, with the help of their magnetic fields, propagate through space. Is that also an instance of e's rising and then falling? Many thanks.It's a pretty primitive description but at least metaphorically accurate (the electrons don't actually rise and fall). The two descriptions (excitation/emission and electromagnetic waves) are two ways of looking at the same phenomenon.
Crosson
Jul4-08, 02:19 PM
No, these two kinds of light emission are very different.
Almost all the light that we normally encounter comes from "e's in the antenna being vibrated back and forth so that the electric field lines emanating from them wiggle."
The other kind of light emission, due to rising and falling electron energy levels, is seen more rarely. Examples are lasers, neon lights, and in nature we see these emissions from stars and galaxies. The main thing about these kinds of emissions is that the color or frequency of the light is very precise, corresponding to the size of the fall in the energy level of the electron.
Vosh
Jul4-08, 09:23 PM
No, these two kinds of light emission are very different.
Almost all the light that we normally encounter comes from "e's in the antenna being vibrated back and forth so that the electric field lines emanating from them wiggle."
The other kind of light emission, due to rising and falling electron energy levels, is seen more rarely. Examples are lasers, neon lights, and in nature we see these emissions from stars and galaxies. The main thing about these kinds of emissions is that the color or frequency of the light is very precise, corresponding to the size of the fall in the energy level of the electron.
Well, this tips my Universe upside down. Firstly, I don't have formal training under my belt. I'm, shall we say, PBS Nova educated. That said, I'm not sure what you mean; do you mean that most of the EM radiation we encounter - as in radio waves impacting us, etc.? And the visible light is caused by the e's falling back to a lower orbit? Many thanks for your patience.
cesiumfrog
Jul4-08, 10:31 PM
You could say that all light is due to redistributions of electric charges.
cepheid
Jul6-08, 01:50 AM
No, these two kinds of light emission are very different.
Almost all the light that we normally encounter comes from "e's in the antenna being vibrated back and forth so that the electric field lines emanating from them wiggle."
The other kind of light emission, due to rising and falling electron energy levels, is seen more rarely. Examples are lasers, neon lights, and in nature we see these emissions from stars and galaxies. The main thing about these kinds of emissions is that the color or frequency of the light is very precise, corresponding to the size of the fall in the energy level of the electron.
Question: Is the former what is referred to as "thermal emission", resulting in a continuum spectrum?
The latter of course, the emission due to atomic transitions, results in line spectra.
Crosson
Jul6-08, 02:40 AM
Question: Is the former what is referred to as "thermal emission", resulting in a continuum spectrum?
The latter of course, the emission due to atomic transitions, results in line spectra.
Yes, exactly.
Well, this tips my Universe upside down. Firstly, I don't have formal training under my belt. I'm, shall we say, PBS Nova educated. That said, I'm not sure what you mean; do you mean that most of the EM radiation we encounter - as in radio waves impacting us, etc.? And the visible light is caused by the e's falling back to a lower orbit? Many thanks for your patience.
No, I mean that most instances of EM radiation, including visible and radio parts of the spectrum, are the result of thermal emission, and they don't have anything to do with electrons falling into a lower orbit.
When electrons change their energy level in an atom they produce a discrete spectrum as see here:
Atomic Spectrum of Hydrogen (http://www.physics.uc.edu/~sitko/CollegePhysicsIII/28-AtomicPhysics/AtomicPhysics_files/image006.jpg)