Question

Electrons with energy $80keV$ are incident on tungsten target of an $X-$ ray tube. $K-$ shell electrons of tungsten have ionization energy $72.5keV$. $X-$rays emitted by the tube contain only

• A. A continuous X-ray spectrum (Bremsstrahlung) with a minimum wavelength of $\sim 0.155A^o$
• B. A continuous X-ray spectrum (Bremsstrahlung) with all wavelength
• C. The characteristic X-ray spectrum of tungsten.
• D. A continuous X-ray spectrum with minimum wavelength of $\sim 0.155A^o$ and the characteristic X-ray spectrum of tungsten

Answer 1

The correct option is D A continuous X-ray spectrum with minimum wavelength of $\sim 0.155A^o$ and the characteristic X-ray spectrum of tungsten

$enegry=\frac{hc}{\lambda }$
$\lambda =\frac{hc}{energy}$
$=\frac{1240eV-nm}{80\times {10}^{3}eV}(hc=1240eV-nm)$
$=0.0155nm$
$=0.155A^{\circ }$
So, X-rays emitted have a continuous X-ray spectrum with minimum wavelength of $0.155A^{\circ }$ and characteristic X-ray spectrum of tungsten because electrons are incident on tungsten target.

So, the answer is option (D).