What happens when a potential difference is applied to a piezoelectric crystal?
The crystal changes shape when a potential difference is applied.
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How are ultrasound waves generated?
A piezoelectric crystal changes shape to produce pulses of ultrasound.
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How are ultrasound waves detected?
A piezoelectric crystal changes shape and produces an e.m.f. when exposed to ultrasound.
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What is meant by the term acoustic impedance?
A measure of a materials resistance to vibration.
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What is the equation linking acoustic impedance (Z), density (ρ), and speed of sound in medium (c)?
Z = acoustic impedance (kg m-2 s-1)
ρ = density (kg m-3)
c = speed of sound in medium (m s-1)
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What factors affect ultrasound attenuation?
Attenuation increases with:
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What is the equation linking reflected intensity (Ir), incident intensity (I0), and the acoustic impedances of the materials (Z)?
Ir = reflected intensity
I0 = incident intensity
Z2 = acoustic impedance of material 2 (kg m-2 s-1)
Z1 = acoustic impedance of material 1 (kg m-2 s-1)
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