Question

The $K_{\alpha }$ X- rays arising from a cobalt ($Z=27$) target have a wavelength of 179 $pm$. The $K_{\alpha }$ X rays arising from a nickle target (Z=28) is

• A. > 179 $pm$
• B. < 179 $pm$
• C. = 179 $pm$
• D. None of these

Answer 1

The correct option is B

< 179 $pm$

$\lambda \propto \frac{1}{(Z-1{)}^2}$

$\frac{{\lambda }_{Ni}}{{\lambda }_{Co}}=(\frac{Z_{Co}-1}{Z_{Ni}-1}{)}^2=(\frac{27-1}{28-1}{)}^2$
${\lambda }_{Ni}=\frac{(26{)}^2}{(27{)}^2}{\lambda }_{Co}$ $({\lambda }_{Ni}<{\lambda }_{Co})$