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In the physical sciences and electrical engineering, dispersion relations describe the effect of dispersion on the properties of waves in a medium. A dispersion relation relates the wavelength or wavenumber of a wave to its frequency. Given the dispersion relation, one can calculate the frequency-dependent phase velocity and group velocity of ...
Ultrasound. Ultrasound is sound with frequencies greater than 20 kilohertz. [1] This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound. Ultrasonic devices operate with frequencies from 20 kHz up to several gigahertz.
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound.
The 2-sided bandwidth relative to a resonant frequency of F 0 (Hz) is F 0 /Q. For example, an antenna tuned to have a Q value of 10 and a centre frequency of 100 kHz would have a 3 dB bandwidth of 10 kHz. In audio, bandwidth is often expressed in terms of octaves. Then the relationship between Q and bandwidth is
Reflectometry. Reflectometry is a general term for the use of the reflection of waves or pulses at surfaces and interfaces to detect or characterize objects, sometimes to detect anomalies as in fault detection and medical diagnosis. [1] There are many different forms of reflectometry. They can be classified in several ways: by the used ...
Relationship between wavelength, angular wavelength, and other wave properties. A quantity related to the wavelength is the angular wavelength (also known as reduced wavelength), usually symbolized by ƛ ("lambda-bar" or barred lambda). It is equal to the ordinary wavelength reduced by a factor of 2π (ƛ = λ/2π), with SI units of meter per ...
In frequency (and thus energy), UV rays sit between the violet end of the visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC. UV is the lowest energy range energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions.
The wavelength can be calculated as the relation between a wave's speed and ordinary frequency. λ = c f . {\displaystyle \lambda ={\frac {c}{\ f\ }}~.} For sound waves, the amplitude of the wave is the difference between the pressure of the undisturbed air and the maximum pressure caused by the wave.