* Emission of energy from an atom and the transmission of this energy through space. * Energy propagated in a material medium or space.
* Energy in transit.
What are the types of radiation?
* Radiation is of two general types in our environment.
* They are called non-ionizing and ionizing.
* the energy transferred to the electrons causes them to be pulled away or removed from an atom entirely. * The result is the formation of an ion pair.
* The ion pair consists of a negatively-charged free electron and a positively -charged atom.
* Process occurs when an inner electron of an atom receives enough energy to allow it to move into an excited state at a higher energy level. * However, this transfer is only temporary.
* Electron soon returns to its original energy level by re-emitting the energy gained as electromagnetic radiation. * A familiar example of excitation is the emission of light in the glass tubes in an advertising sign, commonly known as “neon signs”.
* Non-ionizing radiation exists in various forms.
* Some are detected by our senses while other forms are recognized through special instruments that convert this type of radiation into signals that our senses can recognize. * Familiar examples
* Radio waves which carry information and entertainment through radio and television. * Microwaves which are used in microwave ovens and to transmit cellular telephone messages. * Infrared rays which provide energy in the form of heat. * Visible light which we can see
* Ultraviolet rays from the sun which can provide a good suntan
* Radiation that exists in our environment.
* Unlike infrared (heat) or visible light, it is undetected by any of our physical senses. * Can be detected it with simple radiation detection instruments. * Occurs in two forms.
* rays and particles
* Occurs at the high frequency end of the electromagnetic spectrum.
* This type of radiation carries sufficient energy to knock electrons off other atoms - leaving them electrically charged or ionized. * In living tissues, the ions caused by such radiation can affect normal biological processes. * Because ions have an electrical charge, they are easy to detect. * This makes it possible to measure the amount of radiation present in extremely low levels.
Common types of ionizing radiation
* Alpha particles
* Beta particles
* Gamma rays
* X-ray is not strictly nuclear in origin but is included here as a form of ionizing radiation very similar to gamma radiation.
* Alpha ( a ) Particles
* Have positive electric charge and are emitted from naturally-occurring elements such as uranium and radium, as well as from some man-made radioactive elements. * Made up of two protons and two neutrons bound together. * An alpha particle is identical with the nucleus of a helium atom. * Because of its relatively large size, alpha particles travel slowly. * Collide readily with matter and lose their energy quickly.
Alpha ( a ) Particles
* Have little penetrating power.
* Can be stopped by a sheet of paper or by the first layer of the skin. * Thus, present no external hazard.
* However, if they are taken in the body, for example by breathing or swallowing, alpha particles can affect the body’s cells. * Inside the body, because they give up their energy over a relatively short distance, alpha particles can inflict more biological damage than other kinds of radiation.
Beta ( b ) Particles
* They are negatively charged particles identical to electrons. * These particles are much smaller, lighter and more penetrating than alpha particles. * They can pass through 1 to 2 centimeters of water and human flesh. *...