physics paper txtbook Flashcards
3 acoustic variables (PDD)
- pressure
- density
- distance
sound waves are ___, ____, __ waves
acoustic, longitudinal, mechanical
7 acoustic parameters
- period
- frequency
- wavelength
- amplitude
- power
- intensity
- propagation speed
a pair of in phase waves that interfere result in the formation of a single wave of ___ (greater/ less) amplitude. Termed “___” interference
greater
constructive
the resultant wave value of ___ interference is smaller than one of it’s components
destructive
explain how both constructive and deconstructive interference can occur simultaneously
when waves of different frequencies interfere
time it takes a wave to complete a single cycle
period
t/f: the period is determined by the sound source only, not the medium
true
is period is adjustable by the sonographer ?
no
infrasound range
below 20Hz
audible frequency range
20Hz - 20KHz
ultrasound frequency range
ABOVE 20kHz (20, 000Hz)
what 2 things does frequency affect in sonography
- image quality
2. penetration
period and frequency are ___ related
inversely
increase in frequency = ___ in period
decrease
if the frequency is measured in Hz then the period will be measured in __
seconds
if the period is measured in milliseconds then the frequency is measured in ___
kHz
freq x period =
1
of the four waves, which has the shortest period:
- 12kHz
- 6,000 Hz
- 205 Hz
- 1 kHz
12 kHz = highest freq (shortest period)
of the 4 waves, which has the highest frequency?
**think, highest freq =
power and amplitude relationship
power = amp(^2) *squared
if the amplitude increases by factor of 3, what happens to the power
increases by a factor of 9
if the amplitude of a wave is decreased by half, what happens to the power?
decreases by 25% (1/4)
if the amp is decreased by a factor of 2, what happens to the power
decrease by a factor of 4
the concentration of energy in a sound beam
intensity
the rate of energy transfer or the rate at which work is being performed
power
the bigness of the wave
amplitude, power, intensity
difference between the max value and the avg value of an acoustic variable
amplitude
units of power
watts
amplitude, power, and intensity are determined by ___
the sound source (US system)