# X-ray tube emission?

1. Feb 19, 2008

### twinsen

In a lecture today our lecturer illustrated the idea of wave particle duality and gave some experiments that show evidence for the particle side of things. Namely photoelectric and x-ray tube.
If I get this right the basic idea is that free electrons are accelerated through a potential difference to high speeds then collide with a screen of some material. This material decelerates the electrons causing x-ray emission.
What I don't quite get is that how can the emitted photon have wave like properties if it isn't a wave in the classical sense as surely the charge is not oscillating. Wouldnt the deceleration of a charge just cause a bump or small pulse in the EM field. Can a short pulse be taken to be a wave and how can you measure properties like frequency of such a wave.

Alex

PS. I wasnt sure where to post this classical/quantum sorry ;)

2. Feb 19, 2008

### malawi_glenn

But the photon clearly have particle properties aswell, can you combine that into the classical wave theory?

The electron is not continous decreasing, it is losing photons in discrete steps, according to Quantum Electrodynamics, on "microscopic" scales of course =)

3. Feb 19, 2008

### ZapperZ

Staff Emeritus
I think (and I'm only guessing here) that your teacher is trying to illustrate the fact that "breaking radiation" or Bremsstrahlung can easily be described using classical E&M, and thus, makes it a "wave" behavior. It isn't something I would do, but it would be something I won't find difficult to understand why he/she would use it in this way.

Zz.

4. Feb 19, 2008

### twinsen

Yer that sounds like what we were doing.

Ah so the emission is more of a continuous spectrum is this built out of lots of seperate pulses of differing wavelength?

Alex

5. Feb 19, 2008

### ZapperZ

Staff Emeritus
Classical description doesn't necessary imply a continuous spectrum. For example, a waveguide can be accurately described with straightforward wave picture, and you get discrete wavelengths (frequencies) in there. It is just that in Bremsstrahlung, you can apply the "accelerating" (or in this case, decelerating) charge description from classical E&M, which of course, is based on the wave description of E&M radiation.

Zz.