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Wavelength Range - 2x10 ^ - 11 m to 2x10 ^ - 8 m


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 x-rays.

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 dirt.

 Consumer Goods:

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 Waves:

The sun, stars, pulsars and certain other heavenly bodies emit X-rays.

Interesting Information

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.