H2 Quantum Physics X-Ray Spectrum..=(

qdtimes2 SG

[Modified]

1.An X-ray spectrum is produced by an X-raytube with tungsten anode and maintained at a constant accelerating potential.

i)If an X-ray tube with a copper target is used, describe and explain the changes to the Intensity and wavelengths of the Bremsstrahlung radiation and Characteristic lines, and also the changes to the minimum wavelength.

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Will the wavelengths increase because Copper has a smaller nucleus has a smaller charge, so it's electron orbital is bigger
-> there's smaller probability of incident electrons colliding with the ones in the orbital, less deflection of incident electrons
-> less intensity of the characteristic lines, less energy converted to photons (higher wavelength produced)?

And i also dunno how the change to Copper anode can affect the intensity of Bremsstrahlung radiation, and also the minimum wavelength (minimum wavelength is only dependent on the accelerating potential right??)

Very troubled.. Thanks in advance :)

eagle SG

No change to minimum wavelength, because accelerating potential remains the same.

Bremstrahlung radiation won't change. Bremsstrahlung is due to the deceleration of the electrons when they "collide" with the target metal. That is why we get a broad spectrum of wavelengths. The type of target metal doesn't affect.

There is a change in characterisic X-rays. This is due to the energy levels of the metal itself, and when we change from tungsten to copper, there's a change in the energy levels. The K-alpha, K-beta, L-alpha, L-beta characteristics X-rays will change to be at a different frequency (due to different energy levels) and hence a different wavelength, since c = freq * wavelength

qdtimes2 SG

hmm..

but how will the wavelengths of the characteristic X-ray change? given that copper has less proton number than tungsten, will it increase? and so will the intensity of the X-rays remains constant as well?

Thanks.. :)

eagle SG

The intensity of the X-rays should remain the same because we give electrons the same amount of energy per unit time, i.e. the same accelerating potential. This is be conservation of energy.

The wavelengths of the characteristic X-rays will differ accordingly to the energy levels between copper and tungsten. You don't need to know the energy levels, but you will need to know how to calculate if the energy levels are given to you. Without the data on the difference in their energy levels, you won't be able to tell how exactly they change. It's not just about proton numbers, of which you do not need to memorize for physics as well.