Question

The wavelength $K_{\alpha }$ of X-ray tube is $0.76\mathring{A}$. The atomic number of the node material of the tube is

• A. $30$
• B. $40$
• C. $50$
• D. $60$

Answer 1

The correct option is B $40$

From the formula, for $K_{\alpha }$
$\frac{1}{0.76\times {10}^{-10}}=Z^{2}R(1-\frac{1}{4})$

$Z^2=1639.6$

$Z=40.49$