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 nickel target $(Z = 28)$ is

The energy of an $X$-ray photon of wavelength $1.65 \mathring{A}$ is ....... $keV$. $(h = 6.6 \times 10^{-34} \ J \cdot s, \ c = 3 \times 10^8 \ m/s, \ 1 \ eV = 1.6 \times 10^{-19} \ J)$ (in $.5$)

In an $X$-ray tube,the wavelength of characteristic $X$-rays is a property of .......

The $K_{\alpha}$ characteristic $X$-ray refers to the transition:

Penetrating power of $X$-rays increases with an increase in

The wavelength of the $L_\alpha$ $X$-ray line of $Pt^{78}$ is $1.32 \, \mathring A$. The wavelength of the $L_\alpha$ line in the $X$-ray spectrum of another unknown element is $4.17 \, \mathring A$. If the screening constant for the $L_\alpha$ line is $7.4$,then the atomic number of the unknown element is: