What is an X ray photon?

SoSolid said:
But aren't X rays electrons that have lost energy and the release of energy is the x ray?
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X-rays are photons generated by firing electrons at metal.
 
It's just that I am stuck on an A level physics question which gives me the energy of an x ray photon and asks me to calculate the speed of it. I was thinking if an x ray was an electron I could use e=mc^2 I can't think of any other way to work out the speed without knowing its wavelength or frequency?
 
an x-ray photon would just just be a photon with a wavelength of what... 10^-9 - 10^-10

you can calculate the frequency of them using f=c/λ

not sure why you are being asked to work out the speed.. its a constant :o

then just use e=hf to find the energy

or just e=hc/λ

an x-ray is just a photon with a specific wavelength

just like radio waves are.. and visible light etc...

edit: convenient: http://www.lbl.gov/MicroWorlds/ALSTool/EMSpec/EMSpec2.html
check your answer against that (its in eV though, so don't forget to divide by 1.6x10^-19)
 
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You know E = hf = hc/(lambda) so you can work out the frequency.

The de Broglie wavelength is (lambda) = h / p

So, hc/E = h/p, i.e. p = E/c.

Although being a photon, it's speed is c. You sure its asking to work out speed?
 
Dave said:
You know E = hf = hc/(lambda) so you can work out the frequency.

The de Broglie wavelength is (lambda) = h / p

So, hc/E = h/p, i.e. p = E/c (and v = E/c^2 if I am relatively sober)

And since p = mc you can work it out.

Or use the relativistic relationship which links energy/rest energy/momentum. (can't remember)
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it has no m, it's a photon

ah, ninja edit :p
 
actually, quite a few A level physics questions will be these sort of trick questions for one or two marks.

Check the question again.
 
under most circumstances, the speed will be 3x10^8. I can't see that being the question

perhaps its something to do with the photoelectric effect, difficult to tell from the OPs wording
 
As someone who took A level physics only a year ago, I can attest to the fact that they do have these little trick questions.

hence why I suggested it being one.
 
daz said:
X-rays are photons generated by firing electrons at metal.
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Not quite. The method of creation has no bearing on the nature of the reulstant photon. X-Rays can also be created in inter-stellar collisions, for example, as measured by CHANDRA.

To anser the OP, an X-Ray photon is simply a high energy photon.
 
MrMatteh said:
under most circumstances, the speed will be 3x10^8. I can't see that being the question

perhaps its something to do with the photoelectric effect, difficult to tell from the OPs wording
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It may be questioning what the recoil velocity is - an atom of mass m emits a photon with energy E, at what speed does the atom recoil....that kind of question.
 
Visage said:
It may be questioning what the recoil velocity is - an atom of mass m emits a photon with energy E, at what speed does the atom recoil....that kind of question.
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yups

come on OP, tell us the whole question! :)
 
Visage said:
Not quite. The method of creation has no bearing on the nature of the reulstant photon. X-Rays can also be created in inter-stellar collisions, for example, as measured by CHANDRA.
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I know it has no bearing on the resultant photon. However, what we define as X-rays and gamma rays overlap, the only difference being the method of creation.
 
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