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 only

Options

A. A continuous `X` - ray spectrum ("Bremsstrahlung") with a minimum wavelength of ~ 0.155 Å`
B. `"A continuous" `X` - "ray spectrum (Bremsstrahlung)" with all wavelengths
C. The characteristic `X` - rays spectrum of tungsten
D. A continuous `X` - ray spectrum "(Bremsstrahlung) with a minimum wavelength of" `~0.155 Å` and "the characteristic" `X` - ray spectrum of tungsten

Answer

D

Explanation

Minimum wavelength of continuous `X` - ray spectrum is given by `lambda_(min) (i n Å) = (12375)/(E (eV)) = (12375)/(80 xx 10^(3)) ~~ 0.155`
Also the energy of the incident electrons `(80 K eV)` is more than the ionization energy of the `K` - shell electrons (i.e., `72.5 K eV`). Therefore characteristic `X` - ray spectrum will also be obtained because energy of incident electron is enough to knock out the electron from `K` or `L` shells.