Exam 1 Flashcards
Which pulse has a longer wavelength?
from a 2 MHz probe
Sound propagates faster in media (materials) with greater
Stiffness
Sound can be described as
Cyclical oscillations within a set of variables (A wave is the rhythmical variation throughout time)
Which pulse has the lower propagation speed?
2mHz or 10 mhz probe
they are the same
Which statement is true considering the propagation speed of sound through air?
Propagation speed in air is slower than in soft tissue
Image quality is affected by wavelength?
True
Intensity can be changed by the sonographer.
True
If stiffness increases, propagation speed
Increases
The frequency of a transducer is 25,000,000 cycles per second. This can be written as
25 MHz
If the power of a wave is halved, the intensity is reduced to 1/4 its value.
False
Which of the following applies to sound waves less than 20 Hz compared to sound waves greater than 20 Hz?
They have less attenuation
Which waves are audible?
28 Hz
If beam area is reduced by half and the power stays the same, the intensity
Doubles
If both propagation speed and frequency double, the wavelength will
Remain the same
Which parameter of the medium has the most effect on the velocity of sound in that medium?
Bulk modulus of the medium
Shorter wavelengths create higher quality images with better detail.
True
If the amplitude is doubled, the intensity is
Increased 4 times
If a sound wave of 2 MHz is traveling through soft tissue, what is the wavelength?
0.77mm
With a 2 MHz transducer, the wavelength in soft tissue is approximately
0.75mm
The highest speed of sound is through which body structure?
Bone
Wavelength is equal to the propagation speed
Divided by frequency
The wavelength of the 3MHz transducer is shorter than the 6 MHz transducer
False
A bouquet has 30 flowers. The size of the bouquet is decreased by a factor of 3. How many flowers remain?
10
The propagation speed used for soft tissue is
An average based on the usual percentages of each type of tissue
When the elasticity of a medium is high, the _________ is high.
Compressibility
The normal range of intensities used in Doppler ultrasound is
0.2 to 400 W/cm squared
Which statement is correct regarding sound travel through a medium?
The molecules oscillate (vibrate) back and forth to create and transmit the sound wave
What term is the reciprocal of Mega?
Micro
Propagation speed = ______________ X wavelength
Frequency
All of the following are acoustic parameters except
Pressure
The units label used for power is
Watts
All of the following are true of sound waves except
They are transverse
Which of the following will create the fastest speed of sound?
Low density, high stiffness
Sound waves are
Longitudinal, mechanical
If frequency increases, wavelength
Decreases
The unit of measurement for wave frequency is a measurement of
Number
The ultrasound wave travels faster than the audible wave.
False
Which is a definition of period?
The time for one complete cycle to occur
U/S travels slowest through
Lung
If the frequency of an U/S wave is doubled, what happens to the period?
Halves
What is the reciprocal of 5?
1/5
The maximum cyclical change in a quantity is known as
Amplitude
Two quantities are directly proportional if an increase in one quality leads to a/an _________ in the other.
Increase
Which of following waves has the longest period?
6 hz
If the power in a beam is 1 watt and the area is 5cm2, the beam’s intensity is
0.2 W/cm2
