Physics 1 Test Ch 8, 9 Flashcards
Correctly describe an imaging transducer
short duration and length of pulses use backing material (damping) to limit ringing low sensitivity wide bandwidth/broadband low Q-factor improved axial resolution p.119
When PZT exceeds the Curie point what happens to it?
When PZT’s temperature exceeds the Curie point, the PZT is depolarized. PZT’s properties are lost forever and the transducer in ruined.
p.121
Piezoelectric materials change shape when a voltage is applied to them, what is that process called?
Reverse Piezoelectric Effect
p.113
PZT is also known as…
Piezoelectric Ferroelectric Lead Zirconate Titanate Ceramic Active Element Crystal p.113
Which transducer component reduces the ringing of the pulse?
Backing Material, also known as damping element
p.115
Mathematically, the Q-factor is the main frequency divided by what?
Q-factor = main frequency ÷ bandwidth
p.119
Imaging transducers can also be referred to as…
MAYBE “ pulsed wave transducer” ??????
Which crystals will produce sound with a lower frequency?
thicker PZT crystals and PZT with lower speeds
p.125
The acoustic impedance of the matching layer is approximately the same impedance as what?
In between that of the active element and the skin Pg 116 The impedance of the matching layer is about the same as the gel we use in US.
Which of the following determines the frequency of sound created by a pulsed wave transducer?
speed of sound in the PZT
thickness of the PZT
p.123
Which of the following determines the focal length of the sound beam?
transducer diameter
frequency of sound
p.135
Which of the following determines the spread of the sound beam in the far field?
transducer diameter
frequency of sound
p.139
Which of the following transducers has the most shallow focus? (gives us frequency of transducer and crystal diameter)
Transducer with smallest diameter and lowest frequency.
p.138
Which of the following transducers has the shallowest focus? (frequency and large or small crystal)
lower frequency and small diameter crystal
p.136
Which of the following transducers has the deepest focus?
Transducer largest diameter and highest frequency.
p.138
Which transducer has the least divergence in the far field?
Transducer with the largest diameter and higher frequency.
p.140
The frequency of the transducer does not change, if the diameter of the new PZT increases, what happens to the beam diameter in the far zone?
decreases
p.143
The frequency of the transducer does not change, if the diameter of the new PZT increases, what happens to the near zone length?
increases
p.143
The frequency of the transducer does not change, if the diameter of the new PZT increases, what happens to the wavelength?
no change
p.143
Which of the following has the deepest location? (at the end of the near zone, at the end of the far zone, end of focal zone, Fresnel)
The far zone (Fraunhofer zone)
p.144)
What is the shape of the sound beam created by tiny PZT crystals?
V-shaped
p.144
Beam diameter is equal to the transducer diameter at what location?
at 2 near zone lengths
p.132
Damping material in the transducer improves the systems _____ resolution.
longitudinal
p.126
Axial
p. 115
(Same thing, different terms)
If the frequency of the electrical excitation voltage of a pulsed wave transducer is 6MHz, then the operating frequency of the transducer is how many MHZ?
frequency is not determined by electrical signal in pulsed wave transducers
p.126
If the frequency of the electrical excitation voltage of a continuous wave transducer is 6MHz, then the operating frequency of the transducer is how many MHz?
6MHz (freq of voltage = operating freq in cont. waves)
p.127
Impedance of a transducer’s active element is 1,900,000 rayls, and the impedance of the skin is 1,400,000 rayls. What is an acceptable impedance of the matching layer?
1,726,000 rayls (or the number between the 2 impedances)
p.127
Which transducer component has cork and rubber on it?
acoustic insulator
p.115
Which transducer component increases efficiency of sound energy between the active element and the body?
matching layer
p.115
Frequency and near zone length are related in what way? (inversely, directly, etc…)
Directly
p.136
Two transducers have the same diameter, but different frequencies, which beam will have a shallower focus?
lower frequency probe
p.136
We are given frequencies and diameters, which has the least divergence?
larger diameter, higher frequency probe
p.140
We are given frequencies and diameters, which has the most divergence?
smaller diameter, lower frequency probe
p.140
Which of the following determines the frequency of sound created by a pulsed wave transducer?
- Speed of sound in the PZT
- Thickness of the PZT
p. 123
Which factors determine the spread of the sound beam in the far field?
transducer diameter
frequency of sound
p.139
