Ch. 1-4 Physics Test Flashcards
Concentrations of energy in a sound beam
intensity
Intensity units are
watts/squared
Intensity is determined by the
sound source
Relationship between intensity and power
directly proportional
If the amplitude is doubled, the intensity is increased by a factor of
4
If the amplitude is halved, the intensity is reduced by a factor of
1/4
Length or distance of a single cycle
wavelength
Wavelength units
length
Wavelength determined by
both medium and sound source
Wavelength equation
wavelength (mm)= (1.54mm/microsec)/(MHz)
In soft tissue, sound with a frequency of 1 MHz has a wavelength of
1.54mm
rate that sound travels through a medium
propagation speed
Propagation speed is also called
speed or velocity
Speed units
distance over time (m/sec)
Speed determined by
medium
General Rule: ____
gases, liquids, solids
Put the following in order from fastest to slowest: fat, lung, air, soft tissue, bone, tendon
bone, tendon, soft tissue, fat, lung, air
Related to weight
Density
Related to change in shape
stiffness
When stiffness increases, speed
increases
When stiffness decreases, speed
decreases
When density increases, speed
decreases
When density decreases, speed
increases
In-phase waves interfere
constructive waves
Out-of phase waves interfere
deconstructive waves
A wave with a frequency of 15,000 MHz is ultrasonic. T/F
true
If the power of a wave is halved, the intensity is reduced to one-fourth its original value. T/F
false
The sonographer adjusts the output of the ultrasound system by increasing the amplitude by a factor of 3. What happens to the intensity
increased by a factor of 9
Collection of cycles that travel together
pulse
five parameters of pulsed ultrasound are
pulse duration, spatial pulse length, pulse repetition period, pulse repetition frequency, duty factor
time from the start of a pulse to the end of that SAME pulse
pulse duration
pulse duration is the
units of time that the pulse is ON
pulse duration is determined by the
sound source
time from the start of one pulse to the start of the NEXT pulse
pulse repetition period
PRP includes one
pulse duration time and one listening time