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225 Cards in this Set
- Front
- Back
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The effects of the medium (patient) upon the Sound Wave is called? |
Acoustic Propagation Properties (the effect the patient has on the sound wave) |
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The effects of the Sound Wave upon the biologic tissue through which it passes is called? |
Biologic Effects (what the sound wave does to the patient) |
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In what 3 ways does the patient effect the Sound Wave? |
Absorbs Sound Reflects Sound Scatters Sound |
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What does the Sound Wave of the Ultrasound do to the patient? |
Heats up the tissue |
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True/False: The Sound Wave is affected by the Patient the same time the Patient is affected by the Sound Wave. |
TRUE |
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True/False: The Sound Wave is ALWAYS affected by the Patient, the Patient is ALWAYS affected by the Sound Wave. |
TRUE |
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What type of wave are Sound Waves? |
Longitudinal |
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Sound must travel through ___________ where molecules are alternately compressed and rarefied (stretched apart). |
a medium |
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Sound is a _____________ wave in which particles in the medium move. |
Mechanical wave (back and forth motion) |
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All waves carry __________ from one location to another. |
Energy |
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What arises from boundaries between structures in the body and return to the transducer and processed into an image? |
Reflections |
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Force divided by Area is? |
Pressure |
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Mass divided by Volume is? |
Density |
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Concentration of Force in an Area is called? |
Pressure |
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Concentration of Mass in a Volume is called? |
Density |
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Measure of particle motion is called? |
Distance |
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What are the Acoustic Variables? |
Pressure (pascals, mmHg) (very small) Density (kg/cm cubed) Distance (cm,mm) Temperature (avg. kinetic energy) |
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What are the 7 Acoustic Parameters? |
*also same parameters for CW + sound wave |
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True/False: ALL waves are a transfer of energy. |
TRUE |
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True/False: Electromagnetic waves are transverse. |
TRUE |
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Sound requires a ___________ to propagate. |
Medium |
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True/False: Mechanical waves travel through a series of pressure variations; compression and rarefactions. |
TRUE |
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True/False: Sound can travel through a vacuum. |
FALSE
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A pair of waves whose Peaks occur at the same time and location are called? (Peak to Peak) |
In-Phase Waves (In-Step) |
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A pair of waves whose Peaks and Troughs occur at different times is called? (Peak to Trough) |
Out-of-Phase Waves (Out of Step) |
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What are the 2 types of Interference on a wave called? |
Constructive Interference Destructive Interference |
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The interference of a pair of In-Phase waves resulting in a single wave of greater amplitude is called? |
Constructive Interference (resulting wave is larger than either of its components) |
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The interference of a pair of Out-of-Phase waves resulting in a single wave of lesser amplitude is called? |
Destructive Interference (resulting wave is smaller than either of its components) |
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Interference pattern of waves with different frequencies is called? |
Beat |
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Speed is determined exclusively by what? |
the Medium (through which the sound travels) |
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The stiffer the material, the higher/lower the speed? |
Higher |
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If elasticity increases, stiffness does what? |
Decreases |
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What are the 7 parameters for Continuous Waves? |
*also same parameters for acoustic + sound waves |
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Power divided by Area is called? |
Intensity |
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Which of the 7 parameters for Continuous waves is determined by the SOURCE? |
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Which of the 7 parameters for Continuous waves is determined by BOTH the Medium and the Source? |
Wavelength (mm, cm) |
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Which of the 7 parameters for Continuous waves is determined by the MEDIUM? |
Speed (m/s) |
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True/False: Period and Frequency are reciprocals. |
TRUE |
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Which of the 7 parameters for Continuous waves describe the Magnitude of the sound wave? |
Amplitude (Pa, cm, dB) Power (watts, dB) Intensity (watts/cm squared, dB) |
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Which of the 7 parameters for Continuous waves can the Sonographer adjust? |
Amplitude (Pa, cm, dB) Power (watts, dB) Intensity (watts/cm squared, dB) |
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Which of the 7 parameters for Continuous waves are considered the "bigness" parameters? |
Amplitude (Pa, cm, dB) Power (watts, dB) Intensity (watts/cm squared, dB) |
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Which of the 7 parameters for Continuous waves can the Sonographer NOT adjust without changing the system? |
Period (sec) Frequency (Hz) (rate) |
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True/False: Power is proportional to the Amplitude squared. |
TRUE |
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What is the typical value for the Period parameter of continuous waves? |
0.06 - 0.5 microseconds |
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What is the typical value for the Frequency parameter of continuous waves? |
2 - 15 MHz (non invasive) 2 - 10 MHz (invasive) |
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What is the typical value for the Wavelength parameter of continuous waves?
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0.1 - 0.8 mm |
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What is the speed of sound through tissue? |
1,540 m/s 154,000 cm/s 1.54 km/s |
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You cannot change the Amplitude without changing which other parameters? |
Power Intensity |
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You cannot change the Power without changing which other parameters? |
Amplitude Intensity |
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Increasing/Decrease the Transducer output, also would increase/decrease which parameters? |
Amplitude Power Intensity |
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If the Amplitude increases by a factor of 3, how much is the Power going to be? |
3 squared = 9 (Power and Amplitude have a square relationship) |
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What is the speed of sound through tissue at 900 Pascals (amplitude) ? |
1,540 m/s (speed of sound is not affected by amplitude, it is only affected by the medium) |
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What is the speed of sound through tissue at 7 Mhz (frequency)? |
1,540 m/s (speed of sound is not affected by the frequency, it is only affected by the medium) |
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If the intensity is doubled, what happens to the speed of sound in tissue? |
Nothing (speed of sound is only affected by the medium) |
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What are the 2 properties of a Medium? |
Stiffness Density |
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What is the relationship between Speed and Stiffness? |
Direct relationship (the stiffer the material, the higher the speed) *The board may use the word elasticity (if the elasticity increases, the speed decreases because the stiffness decreased) |
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What is the relationship between Speed and Density? |
Inverse (if the Density increases, the Speed decreases) |
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True/False: Speed is determined exclusively by the medium. |
TRUE |
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Propagation speed divided by the Frequency is? (medium) (source) |
Wavelength |
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Energy divided by Time is? |
Power |
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Power divided by Area is? |
Intensity |
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Diagnostic Ultrasound Frequency Range is measured in? |
MHz |
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Pulse Repetition Frequency is measured in? |
KHz |
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Blood Velocity is measured in? |
cm/sec |
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Why do we pulse sound? |
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What are the 5 parameters of Pulsed Sound Waves? |
Pulse Duration (microsec) Pulse Repetition Period (PRP) (msec) Pulse Repetition Frequency (PRF) (Hz) Duty Factor (%) Spatial Pulse Length (mm) |
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Which of the 5 parameters of the Pulsed Sound Wave are determined by the SOURCE? |
Pulse Duration Pulse Repetition Period (PRP) Pulse Repetition Frequency (PRF) Duty Factor |
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Which of the 5 parameters of the Pulsed Sound Wave is determined by BOTH the Source and the Medium? |
Spatial Pulse Length (SPL) |
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Which of the 5 parameters of the Pulsed Sound Wave CHANGES by adjusting the Imaging Depth? |
Pulse Repetition Frequency (PRF) Pulse Repetition Period (PRP) Duty Factor |
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Which of the 5 parameters of the Pulsed Sound Wave DOES NOT change with Imaging depth? |
Pulse Duration Spatial Pulse Length |
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True/False: Pulse Duration NEVER changes if system remains the same (same transducer/machine). |
TRUE |
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Pulse Repetition Period has what kind of a relationship with Depth? |
Direct |
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Pulse Repetition Period ALWAYS has an inverse relationship with which 2 parameters? |
Frequency Duty Factor |
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What are the 2 parts of the Pulse Repetition Period? |
Talk (Pulse Duration-never changes) Listen (Time-changes with depth) *when we go deeper, we listen longer |
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True/False: The deeper the scan, the longer the Pulse Repetition Period (listening time). |
TRUE |
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If the Pulse Repetition Period increases, what happens to the Pulse Repetition Frequency? |
Decreases |
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If the Pulse Repetition Period increases, what happens with the Duty Factor? |
Decreases |
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What is the relationship of the Pulse Repetition Period and Depth? |
Direct Relationship *the deeper we scan, the longer we have to listen |
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Pulse Repetition Period is adjustable by the Sonographer by changing what? |
Depth |
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What is the normal Pulse Repetition Frequency range? |
1 - 10 KHz |
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True/False: Spatial Pulse Length is affected by the Wavelength, therefore it is affected by the source and the medium. |
TRUE *spacial pulse is affected by wavelength *wavelength is affected by source and medium |
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Pulse Duration and the Spatial Pulse Length are measured at the exact same point, which is? |
Start of the Pulse and End of the Pulse |
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Pulse Duration is measured in? |
Time (stopwatch) |
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Spatial Pulse Length is measured in? |
Distance (ruler) |
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True/False: Pulse Repetition Frequency has nothing to do with the Transducer Frequency. |
TRUE |
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Pulse Repetition Frequency is determined exclusively by what? |
Scanning Depth |
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SPTA intensity is associated with tissue heating, also called? |
Bioeffects |
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What is the Maximum intensity in time called? |
Temporal Peak Intensity |
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What is the lowest Temporal Intensity? |
Temporal Average |
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True/False: Pulse Average Intensity is ranked in the middle, between the Temporal Peak and Temporal Average Intensities. |
TRUE |
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What does SPTA stand for? |
Spatial Peak Intensity Temporal Average Intensity |
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Review Table 1.1 |
in Physics book pg. 6 |
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Review Ch. 6 lecture over Logarithms/Decibels |
in Physics book pg. 76-78 |
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True/False: Area is measured in units of length squared. |
True |
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True/False: Volume is measured in units of length cubed. |
True |
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How many milliliters are in 8 liters? |
8,000 ml |
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How many centimeters are in 3 meters? |
300 cm |
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How many kilometers are in 3000 meters? |
3 km |
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What is the reciprocal of 100? |
0.01 *1/100 |
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How many hertz is 3 MHz? |
3,000,000 Hz |
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How many milliliters are contained in a jar filled with 5 liters of fluid? |
5,000 ml |
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How many liters are contained in 80 ml of fluid? |
0.08 L |
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How much bigger is a thousand than ten? |
100 times |
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How much bigger is a billion than a million? |
1,000 times |
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How much smaller is a hundred than a thousand? |
one-tenth |
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What do waves transfer from one location to another? a) matter b) molecules c) energy d) water |
c) energy *waves carry energy from place to place |
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Which of the following best describes sound waves? a) a series of compressions and rarefactions b) waves that are heard by man c) movement of molecules and energy from one location to another d) waves that are used to make images of anatomy |
a) a series of compressions and rarefactions |
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Which of the following terms does not belong with the others? a) compression b) region of high density c) region of high pressure d) wide molecular spacing |
d) wide molecular spacing |
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Variations in all of the following identify specific waves as acoustic waves EXCEPT? a) pressure b) parameters c) density d) acoustic variables |
b) parameters |
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All of the following are true of sound waves EXCEPT? a) they are acoustic b) they are pressure waves c) they are transverse d) they move energy |
c) they are transverse *sound waves are longitudinal |
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All of the following are acoustic parameters EXCEPT? a) pressure b) period c) propagation speed d) frequency |
a) pressure *pressure is an acoustic variable not parameter |
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Which of the following best describes sound waves? a) transverse, pressure waves b) transverse, longitudinal waves c) longitudinal, out-of-phase waves d) longitudinal, pressure waves |
d) longitudinal, pressure waves |
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Two waves are traveling in a medium and arrive at a location at the same time. What event takes place? a) constructive interference b) destructive interference c) interference d) reflection |
c) interference |
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Which types of waves will exhibit both constructive and destructive interference? a) waves of different amplitude b) a pair of longitudinal waves c) waves of different frequency d) out-of-phase waves |
c) waves of different frequency |
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True/False: Both constructive and destructive interference occurs with waves with different frequencies. |
True |
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What units are used to report the pressure of a sound beam? a) pounds b) centimeters c) pascals d) kg/cm |
c) pascals (Pa) |
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True/False: Acoustic variables allow us to determine which waves are sound waves and which are not. |
True |
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True/False: Acoustic parameters are used to describe the features of sound waves. |
True |
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What is the period of the earth's rotation around the sun? a) 1 day b) 1 hour c) 1 month d) 1 year |
d) 1 year |
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A top is spinning on a table. What is the period of the spinning top? a) 4 pounds b) 8 dollars c) 0.05 seconds d) 3 cm |
c) 0.05 seconds |
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Which of the following waves is infrasonic? a) 4 MHz b) 400 kHz c) 28 Hz d) 2 Hz |
d) 2 Hz * a wave with a frequency < 20 Hz cannot be heard |
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Identify the wave that is ultrasonic. a) 400 mHz b) 4 MHz c) 28 Hz d) 2 Hz |
b) 4 MHz * a wave with a frequency > 20,000 Hz cannot be heard |
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Which of these waves is ultrasonic and most useful in diagnostic sonography? a) 400 MHz b) 4 MHz c) 2 kHz d) 200,000 Hz |
b) 4 MHz |
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Which of the following waves has the longest period? a) 2 MHz b) 4,000 Hz c) 6 Hz d) 1 kHz |
c) 6 Hz *period and frequency have an inverse relationship |
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Of the four waves whose periods are listed below, which has the highest frequency? a) 8 s b) 80 microseconds c) 8 Ms d) 800 ks |
b) 80 microseconds *period and frequency are indirect |
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Of the four waves whose frequencies are listed below, which has the shortest period? a) 12 kHz b) 6,000 Hz c) 205 Hz d) 1 kHz |
a) 12 kHz *highest frequency = shortest period |
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Of the four waves whose periods are listed below, which has the lowest frequency? a) 8 s b) 80 microseconds c) 8 Ms d) 800 ks |
c) 8 Ms *the longest period has the lowest frequency |
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What are the units of wavelength?
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mm
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What are the units of intensity? |
Watts/cm sqd. |
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What are the units of propagation speed? |
m/s |
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What are the units for period? |
second |
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What are the units for power? |
Watts |
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What determines the parameters of wavelength? |
medium + sound source |
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What determines the parameters of frequency, intensity, period, power, and amplitude? |
sound source |
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What determines the parameters of propagation speed? |
medium |
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True/False: Wavelength, frequency, propagation speed, and period can be changed by the operator. |
False *wavelength, frequency, propagation speed, and period CANNOT be changed by the operator |
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True/False: Intensity, power, and amplitude cannot be changed by the operator. |
False *intensity, power, and amplitude CAN be changed by the operator |
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True/False: A wave with a frequency of 15,000 MHz is ultrasonic. |
True |
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True/False: If the amplitude of a wave is increased to 3 times its original value, the intensity is increased by 6 times. |
False *intensity is proportional to the amplitude sqd *if we triple amplitude, intensity increases by a factor of nine |
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True/False: If the power of a wave is halved, the intensity is reduced to one-fourth its original value. |
False *intensity is the power of a beam divided by its cross-sectional area *if we have half the power, we will halve the intensity |
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True/False: Propagation speed increases as frequency increases. |
False *propagation speed is determined by the medium only *frequency and speed are unrelated |
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Medium 1 has a density of 9 and a stiffness of 6. Medium 2 has a density of 8 and a stiffness of 6. In which medium will sound travel slower? |
Medium 1 *the medium with greater has lower propagation speed |
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Which of the following characteristics will create the fastest speed of sound? a) high density, high stiffness b) low density, high stiffness c) high density, low stiffness d) low density, low stiffness |
b) low density, high stiffness *speed is inversely related to density *speed is directly related to stiffness |
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Which of the following characteristics will create the slowest speed of sound? a) high density, high stiffness b) low density, high stiffness c) high density, low stiffness d) low density, low stiffness |
c) high density, low stiffness *speed is inversely related to density *speed is directly related to stiffness |
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If intensity remains the same while the power is doubled, what has happened to the beam area? a) quadrupled b) doubled c) halved d) unchanged |
b) doubled *intensity = power/area |
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A sound beam travels a total of 10 cm in 2 seconds. What is the speed of the sound? a) 10 cm/sec b) 2 cm/sec c) 5 cm/sec d) 0.2 cm/sec |
c) 5 cm/sec 10cm/2 sec = 5 cm/sec |
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True/False: Propagation speed increases as frequency increases. |
False *speed and frequency are unrelated |
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True/False: Propagation speed increases as frequency decreases. |
False *speed and frequency are unrelated |
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True/False: Propagation speed does not change as frequency increases. |
True *propagation speed and frequency are unrelated |
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What is the wavelength of a wave with an unknown frequency traveling in soft tissue? a) 0.51 microseconds b) 0.51 pascals c) 0.51 m/s d) 0.51 mm |
d) 0.51mm *unit of distance |
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The effect of sound waves on tissue in the body are called? |
Bioeffects |
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Which of the following are considered acoustic variables? (3) a) frequency b) density c) particle motion d) period e) pressure |
density, particle motion, pressure |
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Which of the following are considered acoustic parameters? (2) a) frequency b) density c) period d) pressure |
frequency, period |
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The effects of tissue on sound waves are called? |
Acoustic propagation properties |
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The effects of a medium on an ultrasound wave are called? |
Acoustic propagation properties |
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Frequency and period are ______________ related. |
inversely |
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Amplitude and power are _______________ related. |
directly |
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Amplitude and intensity are ____________ related. |
directly |
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Power and intensity are ________________ related. |
directly |
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Wavelength and intensity and _________ related. |
unrelated |
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Wavelength and frequency are ___________ related. |
inversely |
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Acoustic velocity and density are ____________ related. |
inversely |
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Elasticity and speed of sound are ____________ related. |
inversely |
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Acoustic velocity and compressibility are _____________ related. |
inversely |
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Stiffness and sound speed are _______________ related. |
directly |
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Frequency and sound speed are ________ related. |
unrelated |
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Frequency and intensity are ____________ related. |
unrelated |
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Power and frequency are ____________ related. |
unrelated |
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Which of these four values for PRF would have the longest PRP? a) 2 kHz b) 4,000 Hz c) 6 Hz d) 1 kHz |
c) 6 Hz *PRP is inversely related to PRF |
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Four pulses have PRPs listed below. Which of the following four waves has the highest PRF? a) 8 s b) 80 ms c) 5 ms d) 400 ks |
c) 5 ms *PRP and PRF are indirect |
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Which of these four pulses with PRFs listed below has the shortest PRP? a) 12 kHz b) 6,000 Hz c) 20 kHz d) 1 kHz |
c) 20 kHz *PRP is the reciprocal of PRF |
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Four waves have PRPs listed below. Which of the following four waves has the lowest PRF? a) 8 s b) 80 microseconds c) 8,000 ns d) 800 ms |
a) 8 s *PRP is inversely related to PRF |
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True/False: Two waves can have identical PRFs, even if their PRPs are different. |
False *two waves can never have identical PRFs if PRPs are different |
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True/False: Two waves can have identical PRFs, even if their periods are different. |
True *Period and PRF are unrelated *period is not the same as PRP |
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True/False: Two waves can have identical PRFs, even if their frequencies are different. |
True *frequency and PRF are unrelated *frequency and PRF are not the same thing |
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*Boards True/False: PRF and PRP are determined ONLY by the imaging depth. |
TRUE!! |
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If all other factors remain unchanged, what happens to the duty factor when the PRF increases? |
increases |
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If all other factors remain unchanged, what happens to the duty factor when imaging depth increases? |
decreases |
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If all other factors remain unchanged, what happens to the duty factor when the PRP increases? |
decreases |
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*Test
If all other factors remain unchanged, what happens to the duty factor when the sonographer uses a new transducer with a longer pulse duration? |
increases |
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Which of the following terms does not belong with the others? a) high duty factor b) shallow imaging c) low PRF d) short PRP |
c) low PRF *low PRF is associated w/ deep imaging *a,b,d are associated w/ shallow imaging |
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Which of the following terms does not belong with the others? a) low duty factor b) shallow imaging c) low PRF d) long PRP |
b) shallow imaging *a,c,d are associated w/ deep imaging |
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The time from the start of a pulse to the end of that pulse is called? |
Pulse duration |
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The time from the start of a pulse to the start of the next pulse is called? |
Pulse Repetition Period (PRP) |
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Pulse Repetition Period is the reciprocal of? |
Pulse Repetition Frequency |
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By changing the imaging depth, which of the following does the operator also change? (3) a) PRF b) duty factor c) propagation speed d) PRP e) amplitude f) spatial pulse length |
PRF, duty factor, PRP |
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A sonographer adjusts the depth of view of an ultrasound scan from 8 cm to 16 cm. What happens to each of the following parameters? a) period e) amplitude b) frequency f) pulse duration c) wavelength g) spatial pulse length d) speed |
ALL would remain the same |
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A sonographer adjusts the depth of view of an ultrasound scan from 8 cm to 16 cm. What happens to each of the following parameters? a) PRF b) duty factor c) PRP |
PRF decreases duty factor decreases PRP increases |
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A sonographer is using a 3 MHz transducer and changes to a 6 MHz transducer. The imaging depth remains unchanged. What happens to each of the following parameters?
a) speed b) intensity c) PRF d) PRP |
ALL remain the same |
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A sonographer is using a 3 MHz transducer and changes to a 6 MHz transducer. The imaging depth remains unchanged. What happens to each of the following parameters?
a) period b) frequency c) wavelength |
period decreases frequency increases wavelength decreases |
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A sonographer is using a 3 MHz transducer and increases the output power to visualize structures that are positioned deeper in the patient. No other controls are adjusted. What happens to each of the following parameters?
a) period f) pulse duration b) frequency g) PRF c) wavelength h) spatial pulse length d) speed i) duty factor e) PRF j) PRP |
ALL remain the same |
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A sonographer is using a 3 MHz transducer and increases the output power to visualize structures that are positioned deeper in the patient. No other controls are adjusted. What happens to each of the following parameters?
a) power b) intensity |
power increases intensity increases |
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Every 3 dB change means that the intensity will? |
double |
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Every 10 dB change means that the intensity will? |
increase ten times |
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A reduction in the intensity of a sound beam to one-half of its original value is ________ dB. |
-3 dB |
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A reduction in the intensity of a sound beam to one-quarter of its original value is _________ dB. |
-6 dB |
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-10 dB means that the intensity is reduced to _________ of its original value. |
one-tenth |
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dB is a mathematical representation with a __________ scale. a) logarithmic and relative b) division and relative c) longitudinal and relative d) logarithmic and absolute |
a) logarithmic and relative |
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True/False: We need one intensity to calculate decibels. |
False |
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A wave's intensity is 2 mW/cm sqd. There is a change of +9 dB. What is the final intensity? a) 6 mW/cm sqd b) 2 mW/cm sqd c) 16 mW/cm sqd d) 16 uW/cm sqd |
c) 16 mW/cm sqd |
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If the final intensity of a sound beam is more than the initial intensity, then the gain in dB is ____________. (+/-) |
positive |
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If the initial intensity of a sound beam is less than the final intensity, then the gain in dB is ______________. (+/-) |
positive |
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Name the 3 components of attenuation. |
absorption reflection scattering |
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As the path length increases, the attenuation of ultrasound in soft tissue ______________. |
increases |
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Attenuation in lung tissue is ___________ than attenuation in soft tissue. |
greater than |
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Attenuation in bone is ______________ than attenuation in soft tissue. |
greater than |
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Attenuation in air is ______________ than attenuation in soft tissue. |
greater than |
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What are the units of attenuation? |
decibels (dB) |
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True/False: In a given medium, attenuation is unrelated to the speed of sound. |
True *attenuation and propagation speed are unrelated |
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What is the relationship between ultrasound frequency and the attenuation coefficient in soft tissue? |
In soft tissue, the attenuation coefficient in dB per cm is approx one-half of the ultrasonic frequency in MHz |
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What are the units of the half-value layer thickness? |
distance (cm) |
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As frequency decreases, depth of penetration ______________. |
increases |
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As path length increases, the half boundary layer _________________. |
remains the same |
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Impedance is associated with? |
ONLY the medium |
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As the path length increases, the attenuation coefficient of ultrasound in soft tissue ___________________. |
remains the same |
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Equation: Acoustic impedance = |
acoustic impedance = density x propagation speed |
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Two media A and B have the same densities. The speed of sound in medium A is 10% higher than in medium B. Which medium has the higher acoustic impedance? |
medium A *acoustic impedance = prop. speed x density |
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Impedance is important in _____________ at boundaries. |
reflections |
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Which is better to use while examining a carotid artery, a 7.5 or 3.0 MHZ transducer? |
7.5 MHz *the higher the frequency, the shallower the scan |
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A sound wave with an intensity of 50 W/cm sqd strikes a boundary and is totally reflected. What is the intensity reflection coefficient? a) 50 W/cm sqd b) 25 W/cm sqd c) 100% d) 0 |
c) 100% |
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A sound wave with an intensity of 50 w/cm sqd strikes a boundary and is totally reflected. What is the reflected intensity? a) 50 W/cm sqd b) 25 W/ cm sqd c) 100% d) 0 |
a) 50 W/cm sqd |
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A pulse of ultrasound is propagating in soft tissue, such as liver. The pulse strikes a boundary with a different soft tissue at normal incidence. What portion of the intensity is reflected back toward the transducer? |
small percentage is reflected back (< 1%) *difference of impedance directly determines the intensity of reflection *similar mediums (soft tissue) have similar impedances |
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Sound is traveling in a medium and strikes a boundary with normal incidence. If 63% of the wave's intensity is reflected back toward the transducer, what percentage is transmitted? |
37% *63% + ______% = 100% |
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True/False: Reflections occur ONLY when the impedances of two media at the interface are different. |
True |
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True/False: Two different media can have the same impedances, and when that happens, no reflection will be created. |
True |
