InterviewSolution
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InterviewSolution
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Electrons with energy `80 keV` are incident on the tungsten target of an X - rays tube , k- shell electrons of tungsten have `72.5 keV` energy X- rays emitted by the tube contain onlyA. a continous X-ray spectrum (Bremsstrahlung) with a minimum wavelength of `= 0.155 Å`B. a continous X-ray spectrum (Bremsstrahlung) with all wavelengthsC. the characterstic X-ray spectrum of tungstenD. a continuous X-ray spectrum (Bremsstrahlung) with a minimum wavelength of `= 0.155 Å` and the characteristic X-ray spectrum of tungsten. |
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Answer» Correct Answer - D Minimum wavelength of continuous X-ray spectrum is given by `lambda_("min")` (in Å)`=(12375)/("E(in eV)")` Here, E= energy of incident electron (in eV) = energy corresponding to minimum wavelength `implies lambda_("min")` of X-ray `implies E=80 keV=80 xx10^(3) eV` `:. lambda_("min")` (in Å) `=12375/(80xx10^(3))~~0.155` Also the energy of the incident electrons `(80 keV)` is more than the ionization energy of the K-shell electrons (i.e. 72.5 keV). Therefore, characteristic X-ray spectrum will also be obtained because energy of incident electron is high enough to knock out the electron from K or L-shells. |
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