Each case of communicable disease is the result of an orderly progression in. a series of events. This series of events may be described as a three-link chain, each. link representing a factor essential to the transmission of disease. These links (figure 1-1) are: (1) The source of the disease (reservoir) (2) The means by which the disease may be transmitted (mode of.
Radio Waves. Radio waves are a type of electromagnetic (EM) radiation with wavelengths in the electromagnetic spectrum longer than infrared light . They have have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves, radio waves travel at the speed of light. Naturally occurring radio waves are made by lightning or by astronomical objects.
Types of Waves http://scienceprimer.com/types-of-waves âEvery sound we hear, every photon of light that hits our eyes, the movement of grass blown by the wind and the regular beat of the tides are all examples of waves. They are all around us.â Science of Summer: How Do Ocean Waves Form? http://www.livescience.com/38361-how-... âOne of summer's greatest pleasures for the lucky beachgoer is listening to the rhythmic lapping of ocean waves. A number of factors power this trance-inducing phenomenon, but the most important generator of local wave activity is actually the wind.â