There are two types of waves:
-Longitudinal waves
-Transverse waves
Longitudinal Waves------If the vibration is parallel to the direction of motion, the wave is known as a longitudinal wave (see Fig. 1&3). The longitudinal wave is always mechanical because it results from successive compressions (state of maximum density and pressure) and rarefactions (state of minimum density and pressure) of the medium. Sound waves typify this form of wave motion. For longitudinal waves, it is the distance from compression to compression or rarefaction to rarefaction.
figure3
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Transverse Waves------the vibrations are at right angles to the direction of motion. A transverse wave may be mechanical, such as the wave projected in a taut string that is subjected to a transverse vibration (see Fig. 2 &4); or it may be electromagnetic, such as light, X ray, or radio waves. For a transverse wave, the wavelength is the distance between two successive crests or troughs.figure4
Some mechanical wave motions, such as waves on the surface of a liquid, are combinations of both longitudinal and transverse motions, resulting in the circular motion of liquid particles.
The frequency of the wave is the number of vibrations per second.
The velocity of the wave, which is the speed at which it advances, is equal to the wavelength times the frequency.
The maximum displacement involved in the vibration is called the amplitude of the wave.
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