An $X$-ray tube is operated at $1.24$ million volts. The shortest wavelength of the produced photon will be ..... $nm$.

The order of voltage applied across the ends of an $X$-ray tube is ...... $V$.

The wavelengths of $K_\alpha$ lines of two elements are $250 \, pm$ and $179 \, pm$, respectively. The number of elements between these two elements in the periodic table will be:

If the lattice constant of a crystal is $3 \times 10^{-8} \, cm$ and the glancing angle for the first-order diffraction of $X$-rays is $30^{\circ}$,then the value of $\lambda$ will be ..... $\times 10^{-8} \, cm$.

In an $X$-ray tube,electrons bombarding the target produce $X$-rays of minimum wavelength $1\; \mathring{A}$. What must be the energy of the bombarding electrons in $eV$?

$\Delta \lambda$ is the difference between the wavelength of the $K_\alpha$ line and the minimum wavelength of the continuous $X$-ray spectrum when the $X$-ray tube is operated at a voltage $V$. If the operating voltage is changed to $V / 3$,then the above difference is $\Delta \lambda^{\prime}$. Then: