CHAPTER 1: WAVE PHYSICS
The study of wave motion is very important in physics because it involves the transmission of energy and momentum from a source to a detector. Waves are disturbances usually set up by vibrating bodies, which result in the transfer of energy. The occur both in material media and in free space. When they occur in space they usually go by the name Radiations, and involve changing electric and magnetic field with no particle motion.
Light waves are examples of these. In material media, they may involve changes in some physical quantities like pressure and temperature. While the individual particles do not move far, the disturbance itself may have great distances transferring energy and momentum. Sound is an example of such a media-important wave.
Waves can be generally defined as transport or propagation of a physical quantity, which is non-matter, from one point to another, due to the introduction of some form of energy in the medium.
When a vibrating object sets up waves, the waves travel away from it. The particles of the medium can move either in the same direction as the wave or at right angles to it, about a mean position. When the particles move in the same direction as the wave, the wave is said to have displacements along the wave direction. The wave is then said to be LONGITUDINAL. Examples of this type of waves are sound, seismic waves and compressional waves in coiled springs . When the particles moves at right angles to the wave directions, the wave is said to have displacements perpendicular to the wave direction. The wave is said to be TRANSVERSE.
Examples of this type of wave include light, radio wave, ripples on water surface and waves on a string . In the case of light, which is electromagnetic, there are no particle vibrations; rather it is the interaction of the electric and magnetic fields which are oscillating at right angles to each other. These waves are called electromagnetic waves . Other waves such as in string, water and sound waves are called MECHANICAL WAVES .
Many kinds of wave motion phenomena occur in natur, and they can actually be grouped. The waves whose motions are predictable and repeatable are called PERIODIC, while unpredictable ones are called NON- PERIODIC or RANDOM. This latter group is more often than not referred as NOISE . The shape of a wave, as it moves can also be identify it, hence there are plane waves, spherical waves and harmonic waves.
Whether a wave is heard or not also distinguishes it from others, hence there are AUDIBLE or AUDIO waves, Ultrasonic (beyond the range of the hearing) waves and INFRASONIC (below the range of hearing) waves.
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