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Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

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The amplitude change of a decaying plane wave can be expressed as:<br />

In this expression A o is the unattenuated amplitude of the propagating wave<br />

at some location. The amplitude A is the reduced amplitude after the wave<br />

has traveled a distance z from that initial location. The quantity α is the<br />

attenuation coefficient of the wave traveling in the z-direction. The α<br />

dimensions of are nepers/length, where a neper is a dimensionless<br />

quantity. The term e is the exponential (or Napier's constant) which is equal<br />

to approximately 2.71828.

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