What is the si unit for amplitude?

Answer 1

Amplitude is used for different waves. For a water wave, the amplitude might be measured in units of length (meters or centimeters), for a sound wave, in units of pressure, for an electromagnetic wave, in terms of electrical properties, for an electrical signal, in volts, etc. - so it really depends on the kind of wave.

Answer 2

Sound wave amplitude is usually measured indirectly by measuring accoustic pressure in decibels. Decibels is a ratio, so it has no unit.

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To expand that, the linear unit of amplitude, the sound's pressure level, is the µPa (microPascal) but in acoustics it is normal to use the deciBel (dB), a product of a constant and the logarithm of the ratio of (the measured amplitude / a reference amplitude).

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This avoids awkward manipulations of large exponents, and as dB values are logarithmic many of the calculations become additions and subtractions of modest numbers; and it aligns with the human ear's approximately logarithmic response to amplitude over a linearly million-fold pressure-range.

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However the decibel can be used for any signal comparison, so formally the reference level should be quoted unless the context and reference are known to the reader anyway. For sound in air it is 20µPa, the faintest audible to the fully-healthy human ear. Therefore the full "unit" is the dB re 20µPa.

Answer 3

There is no special SI unit of amplitude. It is the maximum lenght of an oscillation swing.

The maximum displacement y is the amplitude:

Answer 4

We need a length or distance measurement here. The unit is meter or a part of it, like centimeter, millimeter.

Answer 5

the unit of amplitude is metre[m] since amplitude has to do with displacement/distance.

Answer 6

Because amplitude is a measure of distance, its S.I unit is meters (m)

Answer 7

Amplitude does not have a unit, it's just the maximum displacement between two waves .