Physics Chapter 1-3
exponent of zero
A number in scientific notation form with an exponent of zero has a value between 1 and 10.
Stiffness and Spped
**remember both words start with the same letter: S and S. They go in the same direction; when stiffness increases, speed increases
Hint: When discussing relationships between amplitude, power, and intensity, the word squared always follows the word amplitude
-power is related to the amplitude squared -Intensity is related to the amplitude squared. -Power is related to the intensity
Intensity typical values
0.01 to 300 W/cm^2
How much bigger is a thousand than ten?
B. A thousand is 100 times bigger than ten
Identify the wave that is ultrasonic.
B. A wave with a frequency greater than 20,000 Hz cannot be heard because its frequency is higher than the upper limit of human hearing.
Which of these waves is ultrasonic and most useful in diagnostic sonography?
B. Although choices A, B, and D are all ultrasonic, only answer B falls within the typical range of frequencies used in diagnostic sonography
Variations in all of the following identify specific waves as acoustic waves except:
B. Parameters
Of the four waves whose periods are listed below, which has the highest frequency? A. 8 s B. 80 ms C. 8 Ms D. 800 ks
B. The wave with a period of 80 ms has the highest frequency. Period and frequency have an inverse relationship. Thus the wave with the shortest period has the highest frequency.
What other terms describe stiffness?
Bulk modulus is the same as stiffness. Elasticity and compressibility are the opposite of stiff. A marshmallow may be described as not stiff, a low bulk modulus, highly elastic, or highly compressible.
What is speed determined by?
By the density and stiffness of the medium.
How many kilometers are in 3000 meters?
C. 3. Kilo means thousand. Three kilometers equal 3,000 meters
How much bigger is a billion than a million?
C. A billion is 1000 times greater than a million.
Which types of waves will exhibit both constructive and destructive interference?
C. Both constructive and destructive interference occurs with waves with different frequencies.
Two waves are traveling in a medium and arrive at a location at the same time. What event takes place?
C. Interference
A top is spinning on a table. What is the period of the spinning top?
C. Of the available answers, the only one that has units of time is 0.05 seconds. This must be the answer.
What units are used to report the pressure of a sound beam?
C. Pressure is appropriately reported with units of pascals, abbreviated Pa.
Which of the following waves has the longest period?
C. The wave with a frequency of 6 Hz has the longest period. Period and frequency have an inverse relationship. Thus, the wave with the lowest frequency has the longest period.
Of the four waves whose periods are listed below, which has the lowest frequency?
C. The wave with the longest period has the lowest frequency. Choice C has a period of 8 million seconds (8 Ms) which is the longest period.
All of the following are true of sound waves except:
C. They are transverse. Sound waves are longitudinal, not transverse.
What do waves transfer from one location to another?
C. Waves carry energy from place to place
How many centimeters are in 3 meters?
D. 300. Centi means hundredth. There are 100 centimeters in 1 meter. Thus, there are 300 cm in 3 meters.
Which of the following waves is infrasonic?
D. A wave with a frequency less than 20 Hz cannot be heard because its frequency is less than the lower limit of human hearing.
Which of the following best describes sound waves?
D. Longitudinal, pressure waves
Which of the following best describes waves A and B?
D. Out of phase, will interfere destructively
Which of the following best describes waves A and C?
D. Out of phase, will interfere destructively
What is the reciprocal of 1/8?
D. The reciprocal of 1/8 is 8.
What is the reciprocal of 100?
D. The reciprocal of 100 is 1/100 or 0.01
Which of the following terms does not belong with the others?
D. Wide molecular spacing
All of the following are measures of length except
D. second. Seconds are units of time, not length
How does density affect speed?
Density and speed are inversely related. As material become more dense (heavier), the speed of sound in the material decreases. Sound travels faster in media with low density. If two media are equally stiff, the denser medium will have a lower speed.
Smoking and the likelihood of cardiovascular disease
Directly related. Generally, individuals who smoke are more likely to have cardiovascular disease
Years employed and days of vacation earned per year
Directly related. Length of vacation time increases with length of employment
Caloric intake and weight
Directly related. Weight increases with the number of calories consumed.
How are the size of a tree and its age related?
Directly. Generally, as a tree ages, its size increases
How many milliliters are in 8 liters?
E. 8000. Milli means thousandth. One liter contains 1,000 milliliters. Thus, 8 liters contain 8,000 ml. With questions such as this, as the metric prefix gets smaller, the number must increase. When the metric prefix gets larger, the number must decrease.
Why is frequency important in diagnostic sonography?
Frequency is important in sonography because it affects penetration and image quality
Frequency (Units)
Frequency is reported in units of per second, 1/second, hertz, or Hz. Hertz is another way to say "per second" 1 cycle/second = 1 hertz 1000 cycles/second= 1 kHz 1,000,000 cycles/second = 1 MHz
Frequency (Determined By)
Frequency of a sound wave is determined by the sound source only, not by the medium through which the sound is traveling.
Relationship between Intensity and Amplitude
Intensity is proportional to amplitude squared Ex. When a wave's amplitude is doubled, the intensity increases to four times its original value.
Relationship between Intensity and Power
Intensity is proportional to power Examples: When a wave's power is doubled, the intensity is doubled. -When a wave's power is quartered, the intensity is quartered.
Cholesterol level and longevity
Inversely related. As cholesterol levels increase, life span generally decreases.
Alcohol intake and sobriety
Inversely related. Increased consumption of alcohol decreases sobriety.
Hours spent exercising and weight
Inversely related. Weight decreases with an increase in exercise.
How is the age of a loaf of bread related to its freshness?
Inversely. As a loaf of bread ages, its freshness decreases
Peak to peak amplitude
Is the difference between maximum and minimum values of an acoustic variable. Therefore, peak to peak amplitude is twice the value of the amplitude.
Power (Determined By)
Just like amplitude, initial power is determined only by the sound source, the ultrasound system. Power decreases as sound propagates through the body. The rate at which power decreases as sound propagates depends on the characteristics of the medium and the wave
Power (Determined By)
Just like amplitude, initial power is determined only by the sound source, the ultrasound system. Power decreases as sound propagates through the body. The rate at which power decreases as sound propagates depends on the characteristics of the medium and the wave.
medium
Material through which a wave travels
Distance
Measure of particle motion; Units: cm, feet, mile
Propagation Speed (Adjustable?)
No, speed of sound cannot be changed by the sonographer. Speed changes only when the wave travels from one medium to a different medium
Wavelength (adjustable?)
No, wavelength cannot be changed by the sonographer when using a basic ultrasound transducer.
Frequency (Adjustable)?
No. The sonographer cannot change the frequency while using a basic ultrasound system and transducer
period (adjustable)
No. The sonographer cannot change the period while using a basic ultrasound system with a particular transducer.
What is the relationship between frequency and period?
Period and frequency are inversely related to each other. As frequency increases, period decreases. As frequency decreases, period increases
Period (Units)
Period is reported in units of time, such as microseconds, seconds, hours, or days
Power (units)
Power has units of watts
Period (Determined by)
Sound source only
straight line
Sound travels in a straight line.
infrasonic/infrasound
Sound waves with frequencies below 20 hertz
What is the wavelength of other frequency sound waves in soft tissue?
Sound with a frequency of 2 MHZ has a wavelength of 0.77 mm in soft tissue: 1.54 mm/2 = 0.77 mm
Ultrasonic/Ultrasound
Sound with frequencies so high that humans cannot hear. Ultrasound;s frequency is higher than 20,000 Hz (20 kHz)
Propagation Speed (Determined by)
Speed is determined only by the medium through which the sound is traveling. Speed is not affected by the nature of the sound wave. All sound, regardless of the frequency travels at the same speed through any specific medium. This means that sound with a frequency of 5 MHz and sound with a frequency of 3 MHz travel at the same propagation speed in the same medium
Propagation Speed (Units)
Speed is measured in units of meters per second, mm/us, or any distance divided by time
How does stiffness affect speed?
Stiffness and speed are directly related. As materials become stiffer, the speed of sound in the material increases.
More About Speed: What is the speed of sound in soft tissue?
The average or typical biologic medium is called soft tissue. The speed of sound in soft tissue is 1,540 m/s. Other ways to report this value are 1.54 mm/us or 1.54 km/s. This value is approximately 1 mile per second.
List these metric terms in decreasing order:
The correct sequence of decreasing order is as follows: giga, kilo, hecto, centi, micro, nano.
List these metric terms in increasing order:
The correct sequence of increasing order is as follows: micro, milli, deci, deca, hecto, mega
constructive interference
The interference that occurs when two waves combine to make a wave with a larger amplitude; in phase waves
destructive interference
The interference that occurs when two waves combine to make a wave with a smaller amplitude; out of phase waves
What is the reciprocal of 20?
The reciprocal of 20 is 1/20. 20 x 1/20 = 1.
Which of the lines in the graph below represent an inverse relationship?
The red, orange, and black lines represent an inverse relationship. These three lines extend from upper left to lower right.
source
The source of a sound wave is the ultrasound system and transducer. The quantity, or level, of some of the parameters are established by the ultrasound system.
Period (Typical values)
The typical value of period in diagnostic ultrasound is 0.06 to 0.5 microseconds. This may also be written as: 6 x 10^-8 to 5 x 10^-7 seconds 0.06 to 0.5 ms 0.00000006 to 0.0000005 seconds
Density and Speed
The words st-
Three "Bigness" Parameters
Three parameters describe the size, magnitude, or strength of a sound wave: 1.) amplitude 2.) Power 3.) intensity
What is the speed of sound in biologic tissues other than soft tissue?
Tissue type: Speed (m/s) 1.) Air: 330 m/s 2.) Lung: 1,450 3.) Fat: 1,450 4.) Water: 1,480 5.) Soft Tissue: 1,540 6.) Liver: 1,560 7.) Blood: 1,560 8.) Muscle: 1,600 9.) Tendon: 1,700 10.) Bone: 3,500
True or False? Acoustic parameters are used to describe the features of sound waves.
True
True or False? Acoustic variables allow us to determine which waves are sound waves and which are not.
True
What characteristics of a medium determine the speed of sound in that medium?
Two characteristics of a medium affect the speed of sound is 1.) Stiffness 2.) Density
Inversely related/ inversely proportional
Two items are associated such that when one item increases, the other decreases. The graph of two inversely related items extends from upper left to lower right. Examples: Golf score is inversely related to skill A car's gas mileage is inversely proportional to its engine size. Grades in school are inversely proportional to partying time
Related/Proportional
Two items that are associated or affiliated. However, the relationship between the items does not have to be specified. Examples: Weight is related to dieting. Santa is related to Christmas Exam score is related to or proportional to studying. Dental health is related to flossing.
Directly related/ directly proportional
Two items that are associated such that when one item increases, the other increases. The graph of two directly related items extends from lower left to upper right Examples: Clothing size if directly proportional to one's weight. Age is directly related to experience. Skills is directly proportional to practice Quality of wine is directly related or directly proportional to age.
How are the height of a person and the color of his automobile related?
Unrelated. Generally, a person's age and car color have no relation to each other.
IQ and shoe size
Unrelated. There is no relationship between shoe size and IQ
Intensity (units)
W/cm2
Wavelength (Units)
Wavelength is measured in units of mm, meters, or any other unit of length.
Why is wavelength important in diagnostic ultrasound?
Wavelength plays a very important role in image quality. Shorter wavelengths are created by high frequency sound. This usually produces higher quality images with greater detail. Therefore, sonographers should try to use higher frequency transducers rather than lower frequency transducers.
Interference of Waves with Different Frequencies
When the frequencies of the waves differ, both constructive and destructive interference occur.
Reciprocal Relationship
When two numbers with a reciprocal relationship are multiplied together, the result is one. Reciprocal numbers are inverse because when one increases, the other decreases. Examples: 2 and 1/2 are reciprocals 10 and 1/10 are reciprocals Period and frequency are reciprocals.
reciprocal
When two reciprocal parameters are multiplied together, the result is 1.
Intensity (adjustable?)
Yes, Initial intensity, like power and amplitude, can be changed. A control on a basic ultrasound systems allows the sonographer to alter the initial intensity of a wave.
Intensity (Adjustable)
Yes, a control on a basic ultrasound system allows the sonographer to alter initial amplitude of a wave
Amplitude ( Adjustable?)
Yes, a control on a basic ultrasound system allows the sonographer to alter initial amplitude of a wave.
Power (Adjustable ?)
Yes, initial power, like amplitude, can be change. A control on u/s system allows the sonographer to alter the initial power of a wave.
Power (Adjustable)
Yes, initial power, like amplitude, can be changed. A control on ultrasound systems allows the sonographer to alter the initial power of a wave.
negative
a number in scientific notation form with a negative exponent has a value less than 1.
positive
a number in scientific notation form with a positive exponent has a value greater than 10
Unit
all numerical values must have corresponding units . a number alone without units, is ambiguous and can create uncertainty. Units of length- distance or circumference: cm, feet Units of area: cm^2, ft^2 Units of volume: cm^3, ft^3
carry energy
all waves carry energy from one location to another
acoustic waves
another name for sound waves
Hint: Wavelength is the only parameter that is determined by
both the source and the medium
Which of the following is not an appropriate unit for volume?
cm. Volume is measured in units of length cubed. Centimeters is simply a measure of length.
divide
decrease by a factor
Parameters
describes features of a sound wave. The values of seven parameters are required to completely characterize a sound wave. period, frequency, amplitude, power, intensity, wavelength, and speed.
Stiffnes
describes the ability of an object to resist compression. In other words, what will happen if the material is squeezed? A stiff material will retain its shape, whereas a non-stiff material will change its shape. A ping-pong ball is stiff, whereas a marshmallow is not.
Density
describes the relative weight of a material. When equal volumes of two materials are compared, the dense material weighs a lot, whereas the non-dense material weighs little. Steel is dense, aluminum is not dense.
speed (m/s)
frequency (Hz) x wavelength (m)
Power (Units)
has units of watts
multipy
increase by a factor
Scientific notation
is a shorthand manner to represent big numbers
Amplitude
is the "bigness" of a wave. It is the difference between the maximum value and the average or undisturbed value of an acoustic variable. Amplitude is also the difference between the minimum value and the average value of the acoustic variable.
Intensity
is the concentration of energy in a sound beam. To calculate intensity, divide the beam's power by the beam's cross-sectional area. Intensity like power and amplitude, describes the "bigness" of wave. Intensity relates to how the power in a wave spreads or is distributed in space. Therefore, intensity depends on both the power in the beam and the area over which the power is applied.
Intensity
is the concentration of energy in a sound beam. To calculate intensity, divide the beam's power by the beam's cross-sectional area. Intensity relates to how the power in a wave spreads or is distributed in space. Therefore, intensity depends on both the power in the beam and the area over which the power is applied.
Wavelength
is the distance or length of one complete cycle. For example imagine a sound wave as similiar to a train. Wavelength is the length of a single boxcar in a train.
Frequency (definition)
is the number of particular events that occur in a specific duration of time.
Propagation Speed
is the rate at which a sound wave travels through a medium
Power
is the rate of energy transfer or the rate at which work is performed. Power, like amplitude, describes the "bigness" of a wave.
Period definition
is the time it takes a wave to vibrate a single cycle or the time from the start of one cycle to the start of the next cycle.;
Intensity (Determined by)
just like amplitude and power, initial intensity is determined only by the sound source, the u/s system. Intensity changes as sound propagates through the body. The rate at which intensity changes as sound propagates depends on the characteristics of both the sound wave and the medium.
Intensity determined by
just like amplitude and power, initial intensity is determined only by the sound source, the ultrasound system. Intensity changes as sound propagates through the body. The rate
squared
mean that a number is multiplied by itself
Transverse Wave
particles move in a direction that is perpendicular (at right angles) to the direction that the wave propagates
Longitudinal wave
particles move in the same direction that the wave propagates
Acoustic Parameters
period, frequency, amplitude, power, intensity, wavelength, propagation speed
Intensity formula
power (w)/area (cm^2)
Acoustic variables
pressure, density, distance
media
sound pulses created by a transducer travel through biologic tissue
Which of the following is an appropriate unit for area?
square yards. Area is measured in units of length squared. The area that carpet covers is measured in square yards.
compressed
squeezed together
rarefied
stretched apart
audible
the sound where humans can hear sound with frequencies between 20 Hz and 20,000 Hz
out of phase waves
their peaks occur at different times, and so do their troughs: they are "out of step"
What is the rule that defines the relationship between frequency and wavelength of sound in soft tissue?
to find the wavelength of a sound wave in soft tissue, divide 1.54 mm by the frequency in MHz
Unrelated
two items that are not associated; Examples: hair color is unrelated to shoe size *weight is unrelated to day of birth *temperature is unrelated to day of the week.
Intensity (Units)
watts/cm^2
in-phase waves
when peaks occur at the same time & place; when troughs occur at the same time & place
interference waves
when waves lose their individual characteristics at that moment and combine to form a single wave combination
horizontal axis
x axis; runs side to side
vertical axis
y-axis, runs up and down
Which of the lines in the above graph represent relationships between two variables?
All of the lines represent relationships between the variables.
Amplitude (Units)
Amplitude can have units of any of the acoustic variables -pressure-pascals -density-g/cm^3 -particle motion-cm, inches- any distance Amplitude, in relative terms, can also be expressed in decibels (dB)
More About Amplitude: What is the difference between amplitude and peak to peak amplitude?
Amplitude is measured from the middle, or undisturbed, value to the maximum value
What is the difference between amplitude and peak to peak amplitude?
Amplitude is measured from the middle, or undisturbed, value to the maximum value Peak- to peak amplitude: is the difference between maximum and minimum values of an acoustic variable. Therefore, peak-to-peak amplitude is twice the value of the amplitude.
More About Intensity
Amplitude, power, and intensity are three parameters that describe the magnitude or strength of a wave. These parameters tend to be directly related; therefore when intensity increases, power and amplitude also increase
What is the relationship between wavelength and frequency?
As long as a wave remains in one medium, wavelength and frequency are inversely related. As frequency increases, wavelength decreases. The lower the frequency, the longer the wavelength. For example, if a wave's frequency is twice that of another, the wavelength will be half as much
How many milliliters are contained in a jar filled with 5 liters of fluid?
B. 5000.
What is the period of the earth's rotation around the sun?
1. D. The earth completes one cycle around the sun in one year.
What is the meaning of an individual with a heart reate of 1 Hz?
1. One event occurs each second. 2.) A heartbeat is the event. The individual's heart contracts at a rate of 1 beat per second (or 60 beats per minute)
What is the meaning of a sound wave with a frequency of 100 Hz?
1.) 100 events occur each second 2.) A cycle is our event. In this case, 100 Hz means 100 cycles per second.
What is the meaning of a flat-screen TV with a frame rate of 120 Hz?
1.) 120 events occur each second. 2.) A frame is our event. Thus, the TV displays 120 frames per second.
longitudinal wave
A wave in which the vibration of the medium is parallel to the direction the wave travels
mechanical wave
A wave that requires a medium through which to travel. example sound is a mechanical wave in which particles in the medium move. The molecules in the medium vibrate back and forth from a fixed position.
How many hertz is 3 MHz?
A. 3,000,000
Identify all the waves that are inaudible.
A. 4 MHz B. 400 kHz D.2 Hz These 3 waves are inaudible and cannot be heard by humans. Choices A and B are ultrasonic, whereas D is infrasonic. Humans cannot hear infrasound or ultrasound.
How much smaller is a hundred than a thousand?
A. A hundred is one-tenth of a thousand.
Which of the following best describes waves B and C?
A. In phase, will interfere constructively
Which of the following best describes waves D and E?
A. In phase, will interfere constructively.
All of the following are acoustic parameters except:
A. Pressure is an acoustic variable. not a parameter.
Which of the following best describes sound waves?
A. Sound waves are a series of compressions and rarefactions.
How are amplitude and power related?
Both amplitude and power are parameters that describe the size, or magnitude, of a wave. When power increases, so does amplitude. Similiarly, when power decreases, amplitude decreases.
Wavelength (Determined By)
Both the source and the medium
What is the difference between wavelength and period?
Both wavelength and period describe a single cycle in a sound wave. Wavelength refers to the length or distance of a single cycle. Period refers to the time that it takes to complete a single cycle. Wavelength and period are differentiated by their units; wavelength has units of distance, whereas period has units of time.
Pressure
Concentration of force in an area; Units: pascals (Pa)
Density
Concentration of mass in a volume; Units: kg/cm^3
How many liters are contained in 80 ml of fluid?
D. 0.080
Frequency (Typical Values)
In clinical imaging, frequency ranges from approximately 2 MHz to 15 MHz. Another way to say this is 2 million to 15 million per second.
Intensity (Typical values)
In clinical imaging, intensity ranges from 0.01 to 300 W/cm^2
Amplitude (Typical Values)
In clinical imaging, pressure amplitude ranges from 1 million pascals (1 MPa) to 3 million pascals (3 MPa)
Power (Typical Values)
In clinical imaging, typical powers range from 0.004 to 0.090 watts (4 to 90 milliwatts) depending on the diagnostic ultrasound technique
Power (Typical Values)
In clinical imaging, typical powers range from 0.004 to 0.090 watts (4 to 90 milliwatts), depending on the diagnostic ultrasound technique.
Wavelength (Typical Values)
In clinical imaging, wavelength in soft tissue ranges from 0.1 to 0.8 mm
What is the wavelength of 1 MHz sound in soft tissue?
In soft tissue, sound with a frequency of 1 MHz has a wavelength of 1.54 mm.
Propagation Speed (Typical Values)
In the body, the speed of sound ranges from 500 m/s to 4000 m/s, depending on the tissue through which it is traveling.
Amplitude (Determined By)
Initially, amplitude is determined only by the sound source, the ultrasound system. However, amplitude decreases as sound propagates through the body. The rate at which amplitude decreases as sound propagates depends on the characteristics of both the sound wave and the medium