Soundwaves Part 2 Flashcards
_______ is produced by the vibration of a synthetic crystal that possesses piezoelectric properties
Ultrasound
Piezoelectric Principle (Greek) \_\_\_\_\_\_\_ = to press, \_\_\_\_\_\_\_ = amber
“pressure electricity” effect 1st described by the Curies in _____
piezo
elektron
1880
In certain materials (tourmaline, cane sugar, salt, topaz, and quartz), When sound/pressure is applied perpendicular to their surface, an _______ charge is created (PZ Effect)
or
Some materials produce a _______ when deformed by applied pressure
and
Certain materials, when exposed to an electrical shock, will begin to _______ and transmit a sound wave
electrical
voltage
vibrate
Piezoelectricity = _______, _______
Reverse Piezoelectricity = _______, _______
In certain materials, when sound is applied to their surface, an electrical charge is created
Certain materials, when exposed to an electrical shock, will begin to vibrate and transmit a sound wave
Some materials produce a voltage when deformed by applied pressure
cause effect effect cause PZ electric Reverse PZ electric PZ effect
_______ is produced by the vibration of a synthetic crystal that possesses piezoeletric properties.
US probes contain elements that have this piezoelectric effect - these elements are called _______.
Medical US transducers convert electricity to _______ and vice versa.
Ultrasound
transducers
sound
Piezoelectric materials may be _______ or _______-made ceramics
Those not naturally piezoelectric, are made so by placing the material in a strong electronic field while they are at a _______ temperature
If this critical temperature (Curie point) is subsequently exceeded, the element will _______ its piezoelectric properties
natural
man
high
lose
When the electric potential is applied to a piezoelectric crystal, the crystal will either _______ or _______ depending of the polarity of the electrical connections.
Ultrasound is generated when a rapidly alternating electrical potential causes the crystal to _______.
expand
contract
vibrate
US “_______” reflected from objects within the body are detected by the same piezoelectric crystal that produced the US waves.
The returning waves deform the crystal, generating a minute _______ potential that is sensed by the instrument and recorded electronically.
echoes
electrical
In diagnostic US, reflections of the _______ beam from interfaces along the US beam path are of primary interest.
US wave wave = body = strikes interface = reflects/transmit
2 items of info required to properly place echoes on display
1._______ from which the echo came
(assumed as a straight line from where the transducer is pointed)
2._______ to the reflector where the echo was produced
Distance to the reflector if defined by the
_______ equation
sound
direction
distance
range
_______ Equation =The distance (z) traveled equals the product of the propagation speed/velocity (c) and then round distance time of travel (t)
z = ct
The distance traveled is a round-trip, 1/2 the _____ would be the distance to the reflector
Time of travel is for a round-trip, 1/2 the _____ would be the traveled time to the reflector
range
distance
time
_______ Equation = Distance to the reflector (d) equals the product of the propagation speed/velocity (c) and 1/2 the round-trip time
d(mm) = cmm/us X t us / 2
ST: d (mm) = 1.54mm/us X t us / 2
range
A system that can generate an US pulse wave and detect the reflected echo after a measured time permits the distance to the interface to be determined.
This is called a pulsed system, and the design is based on the _______-_______ Principle
echo
ranging
