Range - 2x10 ^ - 11 m to 2x10 ^ - 8
Wilhelm Roentgen discovered X-rays in 1895. Roentgen sent electrons through
an evacuated discharge tube. He used a very high voltage across the tube to
give the electrons a large kinetic energy. When the electrons struck the glass wall
of the tube there was a glow on a bright screen a short distance away. The glow
continued even when if a piece of wood was placed between the tube and the
screen. He concluded that highly penetrating rays were from the discharge tube.
How X-rays are Produced
X-rays was created whenever high-energy
electrons suddenly gave up energy. Machines produce x-rays by accelerating
electrons to extremely high speeds and then crashing them into a piece of solid
material called a target. There, the electrons rapidly slowed down because they
collide with atoms in the target, and part of the energy is changed into
How X-rays are Used
X-rays are used in medicine for medical
analysis. Dentists use them to find complications, cavities and impacted teeth.
Soft body tissue are transparent to the waves. Bones also block the rays.
X-rays are used in industry to inspect
products made by various kinds of materials. X-ray machines are used in
airports to check luggage etc.
In Science x-rays are used to analyze the
arrangement of atoms in many kinds of substances, particularly crystals.
Archaeologists used X-rays to examine ancient objects covered by a crust of
X-rays are also used in consumer goods the manufactures treat certain kinds
of plastic to check the quality of many mass produced products.
A danger associated with X-rays is the extremely high voltage that occurs.
In human beings an overdose exposure of X-rays may produce cancer, skin burns, and
a reduction of the blood supply or other serious conditions. In plants or
animals they may damage or even destroy living tissue.
One precaution that can be taken to avoid these dangers is the use of a
lead shield, because X-rays can not penetrate through it. Try to target the
spot needed only, to avoid the dangers.
Celestial Bodies that Transmit
The sun, stars, pulsars and certain
other heavenly bodies emit X-rays.
Most X-rays from sources in space are absorbed by the atmosphere before
they reach the earth.
Sometimes a harmless substance is injected into the body to make certain organs
stand out clearly on a radiograph or fluoroscopic image.
Discover Aug. 1994 page 13
The Japanese satellite provided astronomers with data that indicates the
X-rays in the universe came from a larger number of galaxies than previously
thought. Observations indicated that X-rays were emitted from a small number of
galaxies with black holes.