Find the maximum potential difference which may be applied across an X-ray tube with tungsten target without emitting any characteristics K or L X-ray. The energy levels of the tungsten atom with an electron knocked out are as follows.
Cell containing vacancy K L M
Energy in keV 69.5 11.3 2.3

Explanation

Let for , k series emission, the potential `required=V `
` :. Energy of electrons =eV `
` This amount of energy =energy =Energy of I Shell.`
`So, the mazimum potential difference`
that can be applied without emitting any electron is `11.3eV`