Understanding Radio Waves

Understanding Radio Waves

Most people think of radio as wireless broadcast of sound, most often music and speech. But the term radio is actually much broader than that; the broadcast of sound is actually just one application of the extremely useful electrical phenomenon that is called radio. Radio takes advantage of one of the most interesting of all electrical phenomena: electromagnetic radiation (often abbreviated EMR), which is a type of energy that travels in waves at the speed of light. EMR travels freely through the air and even in the vacuum of space. EMR waves can oscillate at any imaginable frequency. The rate of the oscillation is measured in cycles per second, also known as hertz (abbreviated Hz). The term hertz here does not refer to the car rental company. Instead, it honors the great German physicist Heinrich Hertz, who was the first person to build a device that could create and detect radio waves. Radio is simply a specific range of frequencies of EMR waves. The low end of this range is just a few cycles per second, and the upper end is about 300 billion cycles per second (also known as gigahertz, abbreviated GHz.) That’s a pretty big range, but EMR waves with much higher frequencies exist as well, and are in fact commonplace. EMR waves with frequencies higher than radio waves go by various names, including infrared, ultraviolet, X-rays, gamma rays, and — most importantly — visible light. That’s right; what we call light is exactly the same thing as what we call radio, but at higher frequencies. The frequency of visible light is measured in billions of hertz, also called terahertz and abbreviated THz. The low end of visible light (red) is around 405THz and the upper end (violet) is around 790 THz