The energy of the $K_\alpha$ $X$-ray line of an element is $8578$ units,and the energy of the $L$ level is $-2859$ units. The energy of the $K$ level is . . . . . . units.

When $X$-rays are incident on an object in a dark room,they will appear as ........

In an $X$-ray tube,electrons bombarding the target produce $X$-rays of minimum wavelength $1\; \mathring{A}$. What must be the energy of the bombarding electrons in $eV$?

The filament current in the electron gun of a Coolidge tube is increased while the potential difference used to accelerate the electrons is decreased. As a result, in the emitted radiation

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.

Stopping potentials of $24, 100, 110$ and $115 \ kV$ are measured for photoelectrons emitted from a certain element (with $24 \ kV$ minimum) when it is irradiated with monochromatic $X-rays$. If this element is used as a target in an $X-ray$ tube,what will be the wavelength of the $K_{\alpha}$ line?