Radio
Radios are used for many purposes. Some examples are communication, radar navigation and television broadcasting. Radios affect everyone's life in many ways. Radios help us get the weather reports. They help NASA speak to astronauts, they even allow us to speak to our friends on the telephone.
Radio's send information through a process called electromagnetic waves. These waves are measured by a metric measurement called a hertz, one kilohertz is equal to 1,000 hertz and a megahertz is 1,000,000 hertz. The term hertz is named after the early radio pioneer Heinrich Hertz.
Because electromagnetic waves travel in a straight line and earth is round, long distance travel for radio waves are made in the ionosphere, this is known as short wave signals or low frequency. Wave length in short distance communication is called high frequency and does not use the ionosphere to reflect signals.
Radios are made up of two main components; a transmitter and a receiver that send signals back and forth.
Although radio technology has advanced since the first radio. It would be hard to imagine what life would be like without radios.
Copied from and Thanks to:
http://library.thinkquest.org/5729/
special thanks to:
Blake S.
Grade 5
William Penn School
Think Quest Team #5729
http://library.thinkquest.org/5729/
special thanks to:
Blake S.
Grade 5
William Penn School
Think Quest Team #5729