Radiation, Matter and the Human Body
In physics, radiation is energy that spreads in the form of electromagnetic waves through space or through various types of matter, such as the human body. Radiation is emitted by a radiating source, such as an antenna, transmitting energy in various directions.
When radiation (a wave) hits any obstacle, one or more of the following interactions may take place:
- Reflection – some or all of the radiation energy is reflected back to the originating medium.
- Absorption – some or all of the energy is absorbed by matter. The amount of energy absorbed depends on the properties of the matter and of the radiation: frequency and amplitude.
- Transmission – energy that is neither reflected nor absorbed passes through the obstacle and emerges from the other side.
All the radiation reaching matter is usually partitioned into reflected, absorbed and transmitted components, as described above, according to the properties of the matter and the characteristics (frequency and amplitude) of the radiation. For example, a mirror reflects almost all of the light radiation reaching it.
The amount of energy absorbed by a human body located near a source of radiation depends on the physical properties of the radiation. For instance, most cellular radiation emitted by a mobile phone held near the head, or in the hand, will be absorbed by the body.
References
- Slater JC, Frank NH. Electromagnetism. Dover Books on Physics. 1969.
- Shadowitz A. The Electromagnetic Field. McGraw-Hill, New York, 1975.
