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lavster
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I have read that the attenuation of water (for ultrasound) is 0.0472 Np m–1
(MHz)–2.
What is this in dB/cm/MHz^-2 ? What is Np?
thanks
(MHz)–2.
What is this in dB/cm/MHz^-2 ? What is Np?
thanks
The attenuation coefficient of water is a measure of how much a beam of light or sound is reduced in intensity as it passes through water. It is usually denoted by the symbol "μ" and is measured in units of inverse distance, such as meters^-1 or centimeters^-1.
The attenuation coefficient of water can be affected by several factors, including the wavelength of the light or sound, the temperature and salinity of the water, and the presence of impurities or particles in the water. In general, longer wavelengths, higher temperatures, and higher salinity can result in a higher attenuation coefficient, while the presence of impurities or particles can increase or decrease the coefficient depending on their properties.
The attenuation coefficient of water can be measured using a variety of techniques, depending on the specific application. For example, in underwater acoustics, it can be measured by sending a sound pulse through the water and measuring the decrease in intensity as it travels. In oceanography, it can be measured using specialized instruments such as a CTD (conductivity, temperature, and depth) sensor.
The attenuation coefficient and the transparency of water are inversely related. This means that as the attenuation coefficient increases, the transparency of water decreases. In other words, the more light or sound is absorbed or scattered as it passes through water, the less transparent the water will be.
The attenuation coefficient of water plays a significant role in underwater visibility. In clear water with a low attenuation coefficient, light can travel long distances without being absorbed or scattered, resulting in good visibility. However, in murky water with a high attenuation coefficient, light is quickly absorbed or scattered, resulting in poor visibility. This is why underwater visibility is often better in clear, tropical waters compared to murky, coastal waters.