Which of the following is accompanied by the characteristic $X-$ray emission?

When a metal target is bombarded with high-energy electrons,the electromagnetic waves generated are

What does the hardness of $X$-rays obtained from an $X$-ray tube indicate?

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:

The diagram shows a graph between the intensity of $X$-rays emitted by a molybdenum target and the wavelength,when electrons of $30 \ keV$ are incident on the target. In the graph,one peak corresponds to the $K_\alpha$ line and the other peak corresponds to the $K_\beta$ line.

$X$-rays are produced due to which of the following?