Q.What are the uses of X-rays ?

X-rays — Properties and Uses

X‑rays are high‑frequency, short‑wavelength electromagnetic waves (wavelengths of the order of $0.1$ nm, comparable to atomic spacings) produced when fast electrons are suddenly stopped by a heavy‑metal target. Their very short wavelength gives them high penetrating power and makes them ideal for probing structures on the atomic scale.

Because their wavelength matches the spacing between planes of atoms in a crystal, X‑rays are diffracted by crystals (Bragg's law, $2d\sin\theta = n\lambda$), so X‑ray diffraction is the principal tool for investigating the internal structure of solids and for determining crystal and molecular structures. Other uses include medical radiography and industrial flaw detection. It is X‑rays — not cosmic rays or $\beta/\gamma$ rays — that are used to study the arrangement of atoms …