The minimum wavelength of $X$-rays produced in a Coolidge tube operated at a potential difference of $40 \ kV$ is ....... $\mathring{A}$.

Calculate the wavelength of the $K_{\alpha}$ line for $Z=31$, when $a=5 \times 10^7 \, Hz^{1/2}$ for a characteristic $X$-ray spectrum.

The $X$-ray beam coming from the $X$-ray tube 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 ..... $\times 10^{-8} \, cm$.

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

$X$-ray beam of intensity $I_0$ passes through an absorption plate of thickness $d$. If the absorption coefficient of the material of the plate is $\mu$,the correct statement regarding the transmitted intensity $I$ of the $X$-ray is: