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## Wavends:Bülg
A A medium is called: **linear**if different waves at any particular point in the medium can be added,**bounded**if it is finite in extent,otherwise**unbounded**.**uniform**if its physical properties are unchanged at different points,**isotropic**if its physical properties are**same**in different directions.
## Examples of waves- Sea-waves, which are perturbations that propagate through water (see also surfing and tsunami).
- Sound - a mechanical wave that propagates through air, liquid or solids, and is of a frequency detected by the auditory system. Similar are seismic waves in earthquakes, of which there are the S, P and L kinds.
- Light, radio waves, x-rays, etc. make up electromagnetic radiation. In this case propagation is possible without a medium, through vacuum.
## Characteristic propertiesAll waves have common behaviour under a number of standard situations. All waves can experience the following:
- Reflection - when a wave turns back from the direction it was travelling, due to hitting a reflective material.
- Refraction - the change of direction of waves due to them entering a new medium.
- Diffraction - the spreading out of waves, for example when they travel through a small slit.
- Interference - the addition of two waves that come in to contact with each other.
- Dispersion - the splitting up of a wave up depending on frequency.
## Transverse and longitudinal waves
Rippless on the surface of a pond are actually a combination of transverse and longitudinal waves; therefore, the points on the surface follow elliptical paths. ## PolarizationTransverse waves can be polarized. Unpolarised waves can oscillate in any direction in the plane perpendicular to the direction of travel, while polarized waves oscillate in only one direction perpendicular to the line of travel.## Physical description of a wave
Waves can be described using a number of standard variables including: frequency, wavelength, amplitude and period.
The amplitude of a wave is the measure of the magnitude of the maximum disturbance in the medium during one wave cycle, and is measured in units depending on the type of wave. For examples, waves on a string have an amplitude expressed as a distance (meters), sound waves as pressure (pascals) and electromagnetic waves as the amplitude of the electric field (volts/meter). The amplitude may be constant (in which case the wave is a
The period (
- .
angular frequency (ω, radians/second) is often used; it is related to the frequency f by:
- .
## Travelling wavesWaves that remain in one place are calledstanding waves - eg vibrations on a violin string.
Waves that are moving are called travelling waves, and have a disturbance that varies both with time t and distance z. This can be expressed mathematically as:,
where ,
where ## The wave equationIn the most general sense, not all waves are sinusoidal. One example of a non-sinusoidal wave is a pulse that travels down a rope resting on the ground. In the most general case, any function of x, y, z, and t that is a non-trivial solution to the wave equation is a wave. The wave equation is a differential equation which describes a harmonic wave passing through a certain medium. The equation has different forms depending on how the wave is transmitted, and on what medium. A non-linear wave-equation can cause mass transport. The Schrödinger equation describes the wave-like behaviour of particles in quantum mechanics. Solutions of this equation are wave functions which can be used to describe the probability density of a particle. ## See also | |||||||||

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