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US Physics (Edelman)
Chapter 1-3
83
Physics
Professional
06/17/2011

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Term
Unrelated
Definition
Two items that are not associated.
Term
Directly related or directly proportional
Definition
Two items that are associated such that when one item increases, the other increases.
Term
Related or proportional
Definition
Two items that are associated or affiliated. The relationship does not have to be specified.
Term
Inversely related or inversely proportional.
Definition
Two items are associated such that when one item increases, the other decreases.
Term
Reciprocal relationship
Definition
When these two numbers are multiplied together they equal 1.
Term
Increase by a factor means
Definition
To multiply by that number.
Term
Decrease by a factor means to
Definition
Divide by that number.
Term
What are the prefixes for billions and billionths?
Definition
Giga G & nano n
Term
What are the prefixes for millions and millionths?
Definition
mega M & micro u
Term
What are the prefixes for thousands and thousandths?
Definition
kilo k & milli m
Term
What are the prefixes for hundreds and hundredths?
Definition
hecto h & centi c
Term
What are the prefixes for tens and tenths?
Definition
deca da & deci d
Term
What is scientific notation for 0.000001?
Definition
ten to negative 6 or micro
Term
When converting units if the unit gets larger the number must
Definition
get smaller
Term
billion also written as 10 to the 9th power has the prefix
Definition
giga G
Term
Acoustic propagation properties
Definition
the effects of the medium upon the sound wave
Term
Biological Effects
Definition
the effects of the sound wave upon the biologic tissue
Term
What does a sound wave carry?
Definition
a type of wave that carries energy, not matter, from place to place
Term
Sound is created by
Definition
vibration of a moving object
Term
A sound wave is a series of
Definition
compressions and rarefactions
Term
Sound is what kind of wave?
Definition
mechanical and longitudinal
Term
The typical units for period are
Definition
0.06 to 0.5 micro senconds usec
which is the same as
0.6 x 10 to negative 7 to 5 x 10 to negative 7
Term
Period is determined by
Definition
the sound source
Term
Can period be changed by the sonographer?
Definition
NO
Term
The units for frequency are
Definition
hertz Hz same as per second
Term
Frequency is determined by
Definition
sound source
Term
Typical units for frequency are
Definition
2 to 15 MHz
Term
A wave with a frequency exceeding 20,000 Hz or 20kHz
Definition
Ultrasound
Term
Sound with a frequency between 20 Hz and 20,000 Hz
Definition
Audible sound
Term
Sound with frequencies less than 20Hz
Definition
Infrasound
Term
This "bigness" parameter amplitude may be expressed in
Definition
decibels dB
Term
Propagation speed
Definition
The rate that sound travels through a medium
Term
Units for propagation speed
Definition
m/sec or mm/us (micro second)
Term
Propagation speed is determined by
Definition
the medium only

density and stiffness
Term
Can the propagation speed be changed by the sonographer?
Definition
No because it is determined only by the media
Term
Interference of waves
Definition
when two waves overlap at the same location and time
Term
Constructive interference
Definition
In phase waves combine to form a wave greater than the original two waves
Term
Destructive interference
Definition
out of phase waves interfere and cause the amplitude of the new wave to be less than the original waves
Term
Amplitude is
Definition
The difference between the maximum value and the average or undisturbed value of an acoustic variable.
Term
Units of amplitude can be any of the acoustic variables such as
Definition
pressure - pascals or density - g/cm cubed (3)
Particle motion - distance
dB decibels
Term
Typical values of amplitude are
Definition
1 - 3 million pascals
same as 1 MPa to 3 MPa
Term
Amplitude is initially determined by
Definition
the sound source, 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.
Term
Can the amplitude be controlled by the sonographer?
Definition
Yes
Term
What is peak to peak amplitude?
Definition
The difference between maximum and minimum values of an acoustic variable.
Term
The rate at which energy is performed is
Definition
Power
Term
The units of power are
Definition
watts
Term
The typical values for power are
Definition
0.004 to 0.090 watts (4 to 90 milliwatts)
Term
Power is determined initially by
Definition
the sound source. However power decreases as sound propagates through the body.
Term
Can the sonographer adjust the power?
Definition
Yes, WE HAVE THE POWER
Term
Power is proportional to the amplitude
Definition
SQUARED

if the sonographer increases the amplitude of a wave by a factor of 3 the power is increased 9 fold 3 x 3 =9 AMPLITUDE SQUARED
Term
If a sonographer decreases the amplitude of a wave to 1/2 of its original value how has the power changed?
Definition
Power is proportional to the amplitude squared so the power is decreased to 1/4 or 25% of its original value.
Term
Intensity is
Definition
the concentration of energy in a sound beam
Term
The units for intensity are
Definition
watts per square cm

watts from power and cm squared from beam area
Term
Typical values for intensity are
Definition
0.01 to 300 watts/cm squared
Term
Intensity is determined initially by
Definition
The sound source.
However, intensity changes as sound propagates through the body. The rate at which intensity changes depends on the characteristics of the medium and the shape of the sound beam.
Term
Is intensity adjustable by the sonographer?
Definition
Yes
Term
Amplitude, power and intensity tend to be related how?
Definition
Directly
Term
Intensity is proportional to
Definition
power

If power doubles intensity doubles
Term
Intensity is proportional to amplitude
Definition
squared.

If a waves amplitude is doubled the intensity is increased four times.
Term
Power and Intensity are related to amplitude
Definition
squared
Term
Mathematically intensity and power are
Definition
proportional or related
Term
This parameter is the only one determined by both the source and the medium.
Definition
Wavelength
Term
Wavelength is
Definition
the distance or length of one complete cycle.
Term
Units of wavelength are
Definition
mm, cm (distance)
Term
Typical values of wavelength are
Definition
0.15 to 0.8mm
Term
Wavelength is determined by
Definition
both the source and the medium
Term
Is wavelength adjustable by the sonographer?
Definition
No
Term
What is the relationship between wavelength and frequency?
Definition
As long as the wave remains in the same medium they are inversely related.
Term
What is the wavelength of 1 MHz sound in soft tissue?
Definition
1.54mm
Term
What is the rule that defines the relationship between frequency and wavelength of sound in soft tissue?
Definition
Divide 1.54mm by the frequency in MHz
Term
Propagation speed is
Definition
the distance that a sound wave travels through a medium in 1 second.
Term
Units for propagation speed are
Definition
meters/second or mm/micorsecond or any distance divided by time
Term
Typical values for propagation speed are
Definition
500 m/sec to 4000 m/sec depending on the tissue it is traveling through.
Term
Propagation speed is determined by
Definition
the medium only
Term
Is the propagation speed adjustable by the sonographer?
Definition
No

It is determined by the medium only
Term
List the speed of sound in biologic tissue from slowest to fastest.
Definition
lung > fat > soft tissue average > liver > blood > muscle > tendon > bone
Term
The propagation speed of air
Definition
330 m/sec
Term
Speed of sound in soft tissue (including blood)
Definition
1,540 m/sec
Term
Propagation speed of tendon
Definition
1,850 m/sec
Term
Propagation speed of bone
Definition
2,000 to 4,000 m/sec
Term
Two characteristics determine the speed of sound in tissue they are
Definition
stiffness and density
Term
Stiffness and speed are related how?
Definition
directly

if one goes up the other goes up
Term
Density and speed are related how?
Definition
Inversely

If density goes up speed goes down
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