# What part of the atom creates light?

1. Sep 14, 2008

### azzkika

What part of the atom creates light??

what part of the atom is responsible for making light, and what particular action must it undergo in order to make light.

i have a basic understanding of electromagnetic wavelengths, and am curious as to how they are produced, and what occurs at the atomic level in order to produce and vary the wavelength/frequency

2. Sep 14, 2008

### cesiumfrog

Re: What part of the atom creates light??

Do you have any understanding of the shapes of electron orbitals? Do you know what produces EM waves on the classical level?

3. Sep 15, 2008

### azzkika

Re: What part of the atom creates light??

i have no understanding of orbital shapes, i would guess EM waves are produced by the charge between electron and photon, but this is only a guess, and have no idea why hydrogen produces light when super heated in the sun, yet none when a cool gas on earth, or what variances at atomic level vary EM wavelength.

4. Sep 15, 2008

### cesiumfrog

Re: What part of the atom creates light??

Look, I could try to simplify an explanation in layperson terms, but how would that help?

I suggest you pick up a textbook (on Electrodynamics, or on first year undergraduate physics, if you're not experienced with calculus yet). That is the path that will lead you to understanding the complete answers.

5. Sep 15, 2008

### clem

Re: What part of the atom creates light??

Light is produced when a electron in the atom goes from an excited state of energy E_i to a state of lower energy E_f, emitting a photon of frequency f=(E_i-E_f)/h.

6. Sep 15, 2008

### ronjanec

Re: What part of the atom creates light??

Clem just said what I have read to be true also. Could I just add that this is more than one photon emitted or a stream of photons that then travel in a wavelike up and down pattern away from the electron like I just mentioned in the what is light thread?

7. Sep 15, 2008

### granpa

Re: What part of the atom creates light??

8. Sep 15, 2008

### vanesch

Staff Emeritus
Re: What part of the atom creates light??

Indeed, probably a classical picture is the easiest. You can picture an atom that makes a transition as an oscillating charge cloud, so as a tiny "antenna" that emits radiation with the frequency equal to the oscillation frequency of the charge.
Quantum-mechanically, there's less of a picture: you get an interaction between the atom (state jump) and the em field (photon count +1).

9. Sep 15, 2008

### Marty

Re: What part of the atom creates light??

I wonder why you call this the classical picture. Is this not the quantum mechanical picture as given by the Schroedinger equation?

10. Sep 16, 2008

### vanesch

Staff Emeritus
Re: What part of the atom creates light??

Eh, probably too. I guess you can indeed take the superposition of say, a p_x and an s orbital, and that wavefunction, which is not a stationary state, will show an associated expectation value of current which will indeed oscillate and so on, and which will radiate classical EM radiation of *more or less* the right properties. However, I don't think you'd get out the correct "photon properties".
But that's usually not how things are seen on the QM level: one usually considers the interaction of the "atom system" with the "free QED field" through a coupling term. And that's harder to visualise.