$A$ metal block is exposed to beams of $X$-rays of different wavelengths. $X$-rays of which wavelength penetrate most?

The ionization energies of Cobalt $(Co)$,Copper $(Cu)$,and Molybdenum $(Mo)$ are $7.8 \, keV$,$9.0 \, keV$,and $20.1 \, keV$ respectively. If any of these metals are used as a target in an $X$-ray tube operating at $15 \, kV$,then:

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:

When an $X$-ray tube operates at a tube voltage of $50 \, kV$,the anode current is $20 \, mA$. If the efficiency of the $X$-ray production is $1 \%$,what is the heat produced per second in calories?

The structure of a solid can be explained by using .......

$X$-rays can be used to study crystal structure if the wavelength lies in the range: