Did you know that the space around you is filled at all times with radio waves from nearby broadcasting stations? These waves cause minute vibrations in all the metal objects in the room. You cannot hear the vibrations until they become sound waves, and they become sound waves only when you turn on your radio.
A radio wave might be called a disturbance that moves out into space. When electrons move back and forth rapidly, we have a radio wave. Heat and light also travel through space in the form of waves.
The difference is that radio waves have a much longer wavelength than either heat or light waves.
Radio waves travel through space in much the same way that waves travel when a pebble is dropped into water. The waves radiate in all directions from their source. Although all radio waves travel at a speed of about 186,000 miles a second, the number of radio waves that travel past a point in one second can vary greatly. This number is called frequency. One complete wavelength is called a cycle. So frequency is the number of complete cycles that take place in a second. If the wavelength is short, the waves are close together; the crests are close together and follow each other quickly. If the wavelength is long, crests are far apart and follow one another slowly. So long waves are of low fe-quency because crests do not come as frequently as those of short waves.
High-frequency waves are measured in kilocycles or thousands of cycles per second. On your radio, from left to right, are the numbers 540, 550, 560, and so on to 1600 kilocycles. Each number refers to a wave frequency. A radio program broadcasts its programs only on its own wave frequency.
The existence of radio waves was predicted long before they were actually discovered. The prediction was made in 1864 by James Maxwell. In 1888 a German physicist, Heinrich Hertz, demonstrated that the waves actually do exist, and travel through space.
0 Comments