The maximum wavelength of hard $X$-rays required for the study of bone fractures is $10^{-11} \ m$. The accelerating voltage in the $X$-ray machine must be:

$X$-rays and $\gamma$-rays of the same energies may be distinguished by

The wavelength of the ${K_\alpha}$ line for an element of atomic number $29$ is $\lambda$. Then the wavelength of the ${K_\alpha}$ line for an element of atomic number $15$ is (Take Moseley's constant $b = 1$ for both elements).

The wavelength of the series limit of the Lyman series in the hydrogen spectrum is $911 \ \mathring{A}$. Calculate the atomic number of the element that emits characteristic $X$-rays with a minimum wavelength of $0.7 \ \mathring{A}$.

$X$-rays of wavelength $22 \, pm$ are scattered from a carbon target at an angle of $85^{\circ}$ to the incident beam. The Compton shift for $X$-rays is ......... $pm$.

$X$-rays of which of the following wavelengths are hardest? (in $\mathring{A}$)