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SPI Physics Board Review Questions
and Answers (100% Pass)
Metric notations: giga, mega, kilo, hecto, deca, deci, centi, milli, micro, and
nano
✓ 10 to the... Giga 9, mega 6, kilo 3, hecto 2, deca 1, deci -1, centi -2, milli
-3, micro -6, nano -9
Complimentary metric units: what goes with giga? Mega? Hecto? Deca?
✓ Giga+nano
✓ Mega+micro
✓ Hecto+centi
✓ Deca+deci
Sounds must travel though a (blank) it cant travel through a (blank)
✓ Medium, vacuum
Sounds is a (blank) wave
✓ Mechanical, longitudinal
What are the three acoustic variables? What are their units?
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✓ 1. Pressure: force/area, pascals
✓ 2. Density: mass/volume, kg/cm3
✓ 3. Distance: cm, feet, miles
Transverse versus longitudinal wave
✓ In a Transverse wave the particles move perpendicular to the direction
of the wave (think ocean waves).
✓ In longitudinal waves the particles move in the same direction as the
wave (bunched up slinky).
Compressions versus rarefactions
✓ Compressions are areas of increased pressure or density whereas
rarefactions are areas of decreased pressure or density
Acoustic Parameters: what do these do? What are the 7 with ultrasound?
✓ Acoustic parameters describe the features of a particular wave
(whereas acoustic variables determine which waves are sound waves).
The 7 acoustic variables we are concerned about with ultrasound are:
period, frequency, amplitude, power, intensity, speed and wavelength
Acoustic parameters: Period
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Definition, units, determined by source or medium, can sonographer change
it, relationships
✓ The time required to complete a single cycle.
✓ Units: seconds, microseconds, hours, any unit of time.
✓ Determined by: sound source
✓ Changed by sonographer: no
✓ Relationships: period and frequency are reciprocals (inverse
relationship); when one goes up the other goes down.
Acoustic Parameters: Frequency
Definition, units, determined by source or medium, can sonographer change
it, typical values, relationships, what does freq affect?
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✓ In DMU the frequency of a wave is the number of cycles of an acoustic
variable that occur in one second.
✓ Units: per second, 1/second = Hertz (Hertz is per second, 1,000/sec =
kilohertz; 1,000,000/sec=megahertz).
✓ Determined by sound source.
✓ Changed by sonographer: no
✓ Typical values 2 to 15 MHz
✓ Relationships: frequency and period are inversely related.
✓ Frequency affects penetration and axial resolution (image quality)
Ultrasound is a wave with a frequency greater than (blank) Hertz
✓ 20,000 Hz, (20kHz)
Audible sound is between (blank) and (blank) Hz
✓ 20 and 20,000 Hz
Infrasound is sound with frequncies less than (blank) Hz
✓ Less than 20 Hz
What time of relationship are period and frequency? What are their
equations? What are their complimentary units?
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