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Written by Angel
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Sunday, 11 May 2008 |
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Wa Waves are all about us. We use them to sense the world. Our ears have receptors for sound waves. For it is a wave that brings to us the cry of a baby or the splashing sound of water. Our eyes have receptors for light waves and it is a wave that brings to us the smile of a child or a beautiful sunset. Waves bring us TV, radio and the voice of a loved one on a cell phone. Every dream we have is a brain wave in motion. Every moment of our lives we are bombarded with a wave of waves: sound waves, visible light waves, radio waves, microwaves, cosmic radiation, sine waves, cosine waves, earthquake waves, waves on a string, and ultrasonic waves. The easiest wave to visualize is a water wave. Toss a rock into a pond and watch the waves spread out in a circle of crests and troughs. This is the nature of all waves. A duck on the waves would bob up and down at regular time intervals. In the ocean waves generally travel in a straight line rather than in a circle, but still have the other wave characteristics.  | Springs can demonstrate the two kinds of wave motion: back and forth or up and down. · The spring alternately condenses and rarifies and continues in a straight line. When it reaches the wall it springs back. This is called a longitudinal wave, and a sound wave is an example. · The spring repeatedly moves up and then down. This is called a transverse wave, and a ocean wave is an example. |  | Waves are measure in cycles, so the number of cycles per unit of time is the wave’s frequency (f). One cycle per second is called a Hertz (Hz). A small amount of energy produces fewer cycles per second or a low frequency wave. A larger amount of energy produces more cycles per second and is therefore a higher frequency wave. Energy is measured in electron volts (eVs). A photon of visible light may measure 2 eVs whereas a gamma ray which is a higher frequency than visible light may have a measure of 200,000 eVs or more. |  | Waves can combine. Two waves of the same frequency add together producing a third wave of the same frequency but with a larger amplitude. These waves add constructively. The ‘perfect storm’ produced waves with a large amplitude. |  | If the waves are out of phase, they add destructively and they combine to produce a wave with a smaller amplitude, producing ripples for example. Sometimes they even cancel each other out. |  | If two waves have just a slightly different frequency they produce beats. When tuning a musical instrument, beats indicate that the instrument is out of tune. When the beats disappear, the musician knows the instrument is in tune. The beat frequency is the difference of the two wave frequencies. For example, a 50 Hz wave combined with a 40 Hz wave will produce 50 -40 = 10 Hz beat wave. Note carefully that the 10 Hz beat wave is just another wave, but generally a lower frequency wave. REFERENCE: |
ves and Beats
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Last Updated ( Thursday, 14 August 2008 )
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Waves and Beats 
