Who invented $X-$rays?

If ${\lambda _1}$ and ${\lambda _2}$ are the wavelengths of characteristic $X$-rays and gamma rays respectively,then the relation between them is

In tungsten,the energy of a $K$-shell electron is $20 \, keV$ and that of an $L$-shell electron is $2 \, keV$. When an electron jumps from the $L$ shell to the $K$ shell,the wavelength of the emitted $X$-ray photon will be:

When $X$-rays from a Coolidge tube pass through an aluminum foil of thickness $0.3 \, mm$,$50\%$ of the $X$-rays are transmitted. If the potential difference between the target and the cathode is increased,the fraction of $X$-rays transmitted through the same foil will be .......

Which of the following wavelengths falls in the $X-$ray region in $\mathring{A}$?

The minimum wavelength of $X$-rays produced by an $X$-ray tube depends on which of the following?