The voltage applied across an $X$-ray tube is nearly......$V$.

$A$ metal target with atomic number $Z=46$ is bombarded with a high-energy electron beam. The emission of $X$-rays from the target is analyzed. The ratio $r$ of the wavelengths of the $K_\alpha$-line and the cut-off wavelength is found to be $r=2$. If the same electron beam bombards another metal target with $Z=41$,the value of $r$ will be

If $X$-rays pass through a strong magnetic field,the $X$-rays . . . . . .

The structure of solids is investigated by using

The power input in an $X$-ray tube is increased by:

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