Any wave can carry information in the form of energy. Waves transmit energy through a material, often called a medium. Water waves carry energy through liquid water, sound waves carry energy through air (and many other media), and seismic waves carry energy through the earth. Its important to note that the medium does not travel along with the wave—only energy moves from one place to another on a wave—although the medium does move back and forth or up and down as the wave passes. The amount of energy carried or transmitted on a wave depends on the wave frequency (the number of waves that pass a point in one second) and by the wave amplitude (the distance that the wave moves the medium back and forth as it passes). Light is also a wave, also called an electromagnetic wave, and radio waves are one of many types of light. Light waves are unique among the other waves because they do not require a medium to travel in. Light waves propagate through space—even empty space—using themselves as the medium. Since radio waves can carry energy, we use them to transmit information by varying the frequency and/or the amplitude of the radio wave to encode a message. For example, a radio transmitter turns a human voice into waves by varying the frequency of radio waves in the same pattern as the sound waves measured by a microphone. This is called frequency modulation or FM. Another way to encode information in radio wave is by varying the amplitude of the waves, called amplitude modulation or AM. The numbers on the radio dial represent radio waves at different frequencies measured in MegaHertz (Mhz are equivalent to 1 million waves per second) or kiloHertz (kHz,1000 waves per second). By tuning your radio receiver, you make it sensitive to radio waves produced at different wave frequencies. Many thousands of messages carried on radio waves are passing through and around you right now, but you need a radio receiver to detect and decode them. SENDING MESSAGE BY RADIO WAVES.
Posted on: Sat, 19 Oct 2013 13:05:37 +0000
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