Use
X-rays are electromagnetic radiation of extremely short
wavelength (0.06 to 120 A), emitted as a result of
electron transitions in the inner orbits of heavy atoms
bombarded by cathode rays in a vacuum tube. Those of
the shortest wavelength have the highest intensity and are
called 'hard' x-rays. x-radiation was discovered by
Roentgen in 1898. x-rays have the following properties:
(i) They penetrate solids of moderate density, such as
human tissue; they are retarded by bone, barium
sulphate, lead and other dense materials. (ii) They act on
photographic plates and fluorescent screens. (iii) They
ionize gases through which they pass. (iv) x-rays damage
or destroy diseased tissue. There is also a cumulative
deleterious effect on healthy tissue.
X-rays find wide use in medicine both for diagnosis
and treatment and in engineering where radiographs are used to show up minute defects in structural members. X-ray
tubes must always be carefully shielded because the
radiation causes serious damage to living tissue.