The wavelength of $X$-rays is of the order of .......

The intensity of $X$-rays from a Coolidge tube is plotted against wavelength as shown in the figure. The minimum wavelength found is ${\lambda _c}$ and the wavelength of the ${K_\alpha }$ line is ${\lambda _k}$. As the accelerating voltage is increased:

Moseley's law for characteristic $X$-rays is given by $\sqrt{f} = a(Z - b)$. Choose the correct statement.

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 $.5$)

$W$. $K$. Roentgen discovered

If the potential difference between the anode and cathode of the $X$-ray tube is increased,then which of the following statements is correct regarding the given $X$-ray spectrum graph?