The wavelength of an $X$-ray beam is $10 \, \mathring{A}$. The mass of a fictitious particle having the same energy as that of the $X$-ray photons is $\frac{x}{3} h \, \text{kg}$. The value of $x$ is ....... . ($h =$ Planck's constant)

In tungsten,the energy of a $K$-shell electron is $20 \, keV$ and that of an $L$-shell electron is $2 \, keV$. When an electron jumps from the $L$ shell to the $K$ shell,the wavelength of the emitted $X$-ray photon will be:

The wavelength of the $K_\alpha$ line for an element of atomic number $Z_1 = 29$ is $\lambda$. What is the wavelength of the $K_\alpha$ line for an element of atomic number $Z_2 = 15$? (Take Moseley's constant $b = 1$ for both elements.)

The wavelength of $L_{\alpha}$ line in $X$-ray spectrum of $_{78}Pt$ is $1.32 \ \mathring{A}$. The wavelength of $L_{\alpha}$ line in $X$-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:

The characteristic $X$-rays depend on .........

$X$-rays of wavelength $0.140 \,nm$ are scattered from a block of carbon. What will be the wavelengths of $X$-rays scattered at $90^{\circ}$ (in $\,nm$)?