Moseley's law relates the frequencies of line $X$-rays with the following characteristics of the target element:

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

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

The structure of a solid can be explained by using .......

When $0.50\; \mathring{A}$ $X$-rays strike a material,the photoelectrons from the $K$-shell are observed to move in a circle of radius $23\; mm$ in a magnetic field of $2 \times 10^{-2}\; T$ acting perpendicularly to the direction of emission of photoelectrons. The binding energy of $K$-shell electrons is $..........\; keV$.

$X$-rays do not undergo diffraction because of their .....