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Sonar > TL - Absorption > Flashcards

TL - Absorption Flashcards

1
Q

What is the absorption coefficient

A

Fraction of energy absorbed per unit length

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2
Q

Absorption formula

A
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3
Q

What is Ionic relaxation?

A

Changes in state of chemicals in the weawater, caused by pressure variations. Absorbs energy from the acoustic wave.

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4
Q

How does ionic relaxation depend on frequency? What is relaxation frequency.

A

Changes of state take a finite amount of time. If pressure changes are too fast, no changes in state occur. This corresponds to a higher frequency.

The frequency which this occurs is called the relaxation frequency.

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5
Q

What are the two main chemicals responsible for ionic relaxation?

A

Boric Acid - relaxation frequency 1kHz
Magnesium Sulphate - relaxation frequency 100kHz

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6
Q

What are the 3 mechanisms of absorption?

A

Viscosity
Ionic relaxation
Scattering

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7
Q

Scattering

A

Not actually absorptoin but reradation of incident sound ray due to inhomogeneities in the index of refraction of water.

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8
Q

What is the absorption expression?

A
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Sonar (15 decks)

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