$X-$rays are known to be electromagnetic radiations. Therefore,the $X-$ray photon has

When an $X$-ray of wavelength $0.5 \, \mathring{A}$ passes through a metal foil of thickness $3.5 \, mm$,its intensity is reduced to one-fourth of its initial value. The absorption coefficient of the metal is ..... $mm^{-1}$.

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

An $X$-ray tube is operated at $50\, kV$. The minimum wavelength produced is ....... $\mathring{A}$.

The patient is asked to drink $BaSO_4$ for examining the stomach by $X$-rays because $X$-rays are

The $K, L$ and $M$ energy levels of platinum lie roughly at $78, 12$ and $3 \ keV$ respectively. The ratio of the wavelength of the $K_{\alpha}$ line to that of the $K_{\beta}$ line in the $X$-ray spectrum is: