# X-ray tube

1. Jun 11, 2010

### oddiseas

1. The problem statement, all variables and given/known data

Sketch and label the x-ray spectrum for an x-ray tube with copper as its target, operating at an excitation potential of 20kV.Assume that the copper energy levels are K shell=-9000ev,L shell=-1000ev,M shell=-200ev.

2. Relevant equations

This question has me a bit confused. Basically in this example we can have 3 possible transitions,
K(a) emmision, K(b) emmision and L(a) emmision from state three to state 1.

However i am wondering given that the excitation potential is way bigger than the energy levels wont any impact with either of the bound electrons cause them to leave the atom?
In addition the solution has a minimum possible wavelength of 0.6 Amgstrom.Where does this come from since the three posible transitions have wavelength 0.155nm,0.141nm,1.5nm.

3. The attempt at a solution

2. Jun 11, 2010

### hikaru1221

Have a look at this: http://en.wikipedia.org/wiki/Bremsstrahlung
The minimum wavelength of the photon corresponds to the maximum energy, which is in this case 20.000 eV. Thus, the minimum wavelength is about 0.62 Angstrom. In this extreme case, the incoming electron is stopped nearly immediately and emits only one photon, not radiates gradually along its path.

Have a look at this too: http://en.wikipedia.org/wiki/File:TubeSpectrum.jpg

I don't get what you meant here: "However i am wondering given that the excitation potential is way bigger than the energy levels wont any impact with either of the bound electrons cause them to leave the atom?"

3. Jun 11, 2010

### graphene

the excitation potential has got to be high. you need an v.energetic electron to knock off an electron from the K-shell.