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.
Many different kinds of energy travel in waves. Sound waves carry noises through the air to our ears. SEISMIC WAVES travel inside the Earth and cause earthquakes.Light, heat, radio, and similar types of energy are carried by a variety of waves in the ELECTROMAGNETIC SPECTRUM.any different kinds of energy travel in waves. Sound waves carry noises through the air to our ears. SEISMIC WAVES travel inside the Earth and cause earthquakes.