Physics Ch. 1-3 Test
What is the wavelength of a 10 MHz ultrasound beam in soft tissue? Select one: a. .15 mm b. .15 cm c. 1.5 mm d. 1.5 cm
a. .15 mm
What is the propagation speed of a 5 MHz sound wave in soft tissue? Select one: a. 1.54 mm/µs b. 1.54 mm/s c. 1450 m/s d. 1540 km/s
a. 1.54 mm/µs
Ultrasound is defined as sound with a frequency of: Select one: a. > 0.02 MHz b. < 1kHz c. < 20,000 Hz d. > 10 MHz
a. > 0.02 MHz
Stiffness of a medium is the opposite of its: Select one: a. Compressibility b. Frequency c. Hardness d. Impedance
a. Compressibility
When an acoustic wave travels through a medium, the tissue molecules change concentration. What is the highest level of concentration called? Select one: a. Compression b. Ionization c. Excitation d. Rarefaction
a. Compression
Which factor affects the acoustic velocity in a medium? Select one: a. Density of the medium b. Cross-sectional area of ultrasound beam c. Wavelength d. Frequency
a. Density of the medium
All of the following are acoustic variables except: Select one: a. Impedance b. Pressure c. Distance d. Density
a. Impedance
By doubling the amplitude, the intensity will: Select one: a. Increase by 4 b. Increase by 2 c. Decrease by ¼ d. Decrease by ½
a. Increase by 4
If the acoustic amplitude is increased, this is also is increased: Select one: a. Intensity b. Impedance c. Velocity d. Wavelength
a. Intensity
Which type of wave exhibits particle motion along the direction of propagation? Select one: a. Longitudinal b. Sheer c. Transverse d. Light
a. Longitudinal
When going from a medium of low acoustic velocity to a medium with a high acoustic velocity, the frequency of the sound beam: Select one: a. Remains constant b. Decreases c. Increases
a. Remains constant
The speed at which an ultrasound beam travels in a patient's liver depends mainly upon the: Select one: a. Stiffness and density of the liver tissue b. Impedance and attenuation of the liver tissue c. Frequency and wavelength of the sound beam d. Amplitude and intensity of the sound beam
a. Stiffness and density of the liver tissue
What are the units of the intensity of a sound wave? Select one: a. W/cm2 b. cm2 c. Watts d. dB
a. W/cm2
If a structure encountered is 30 mm in diameter, how many centimeters would it be? Select one: a. 300 cm b. 3 cm c. 30 cm d. .03 cm
b. 3 cm
Which of the following is the number 6115 expressed in scientific notation? Select one: a. 61.15 x 10^3 b. 6.115 x 10^3 c. 6.0 x 10^-3 d. 6.1 x 10^3
b. 6.115 x 10^3
A fraction consists of a numerator and a denominator. An increase in the denominator would cause the number to: Select one: a. Stay the same b. Decrease c. Increase
b. Decrease
With velocity being constant, if frequency is halved, wavelength is: Select one: a. Halved b. Doubled c. Increased by a factor of 4 d. Decreased by a factor of 4
b. Doubled
When the power in an acoustic beam is doubled and the cross-sectional area of the beam is halved, the intensity of the beam is: Select one: a. Halved b. Four times larger c. Doubled d. Quartered
b. Four times larger
Audible sound is: Select one: a. Greater than 20,000 hertz b. Greater than 20 hertz and less than 20,000 hertz c. Less than 20 hertz d. Less than 200 hertz
b. Greater than 20 hertz and less than 20,000 hertz
Power is related to amplitude. If wave's amplitude is doubled, the power is: Select one: a. Doubled b. Increased by a factor of 4 c. ¼ d. Halved
b. Increased by a factor of 4
The unit for pressure is: Select one: a. Watt b. Pascal c. W/cm3 d. Kg/cm
b. Pascal
What is the rarefaction zone? Select one: a. Region of high particle density b. Region of low particle density c. Region of high acoustic impedance d. Region of low acoustic impedance
b. Region of low particle density
Which of the following options correspond to the correct units of measure for the following: Sound speed, Intensity, Frequency, Wavelength, Amplitude Select one: a. cm/sec, W/sec, MHz, m, pascal b. Hz, dB, mm/cm2, m/sec2, mm c. m/sec, W/cm2, MHz, mm, pascals d. W, dB, m/s, cm, dB/cm
c. m/sec, W/cm2, MHz, mm, pascals
If the period of a wave decreases, the frequency will: Select one: a. Remain the same b. Double c. Increase d. Decrease
c. Increase
A longitudinal wave is characterized by: Select one: a. Particle motion occurring perpendicular to propagation b. A frequency of vibration greater than 1MHz c. Particle motion occurring in the same direction as propagation d. The ability to penetrate at least 5 cm in tissue
c. Particle motion occurring in the same direction as propagation
Increasing the frequency increases the penetration depth. Select one: True False
False
The average propagation speed in soft tissues is: Select one: a. 1.54 km/µs b. 1.54 m/s c. 1540 m/s d. 1540 mm/s
c. 1540 m/s
Infrasound is defined as a sound with frequency of: Select one: a. < 0.02 MHz b. > 10 MHz c. < 20 Hz d. > 20,000 kHz
c. < 20 Hz
The highest velocity occurs in which of the following? Select one: a. Tissue b. Fat c. Bone d. Air
c. Bone
When two waves overlap at the same location and at the same instant in time, they combine with each other. The result is a new wave with greater amplitude than the original two waves. This is called: Select one: a. Out-of-phase waves b. Destructive waves c. Constructive waves d. Phase differences
c. Constructive waves
If the frequency of a wave is halved, the wavelength will: Select one: a. Increase by a factor of 4 b. 1/4 c. Double d. Halve
c. Double
The number of cycles per second is defined as: Select one: a. Wavelength b. Period c. Frequency d. Amplitude
c. Frequency
If the frequency is 5 MHz, the period is: Select one: a. .1 µs b. 1 µs c. 2 µs d. .2 µs
d. .2 µs
What is the wavelength of a 3.5 MHz sound wave in soft tissue? Select one: a. 4.4 mm b. 0.22 mm c. 2.2 mm d. 0.44 mm
d. 0.44 mm
What is the typical frequency range used in ultrasound imaging: Select one: a. Over 20 MHz b. Less than 1 MHz c. 60 Hz d. 1 to 10 MHz
d. 1 to 10 MHz
The speed 1540 m/s is equivalent to: Select one: a. 1.54 cm/s b. 1540 cm/s c. 1.54 mm/s d. 1.54 mm/µs
d. 1.54 mm/µs
The velocity of ultrasound in soft tissue is approximately: Select one: a. 1450 m/s b. 440 m/s c. 330 m/s d. 1540 m/s
d. 1540 m/s
If density is increased, everything else remaining the same, propagation velocity will: Select one: a. Remain the same b. Increase c. None of the options are correct d. Decrease
d. Decrease
If the compressibility of a material increases, the speed of sound will: Select one: a. Increase b. Remain the same c. Double d. Decrease
d. Decrease
The concentration of the power in a beam is referred to as: Select one: a. Amplitude b. Power c. Pulse duration d. Intensity
d. Intensity
The energy per unit area of a sound beam is called: Select one: a. Work b. Amplitude c. Power d. Intensity
d. Intensity
Which of the following is characteristic of diagnostic ultrasound? Select one: a. It is a form of electromagnetic radiation. b. It is a transverse wave. c. It can be transmitted through a vacuum. d. It is a mechanical, longitudinal wave.
d. It is a mechanical, longitudinal wave.
Ultrasound travels the slowest through which of the following? Select one: a. Soft tissue b. Fat c. Bone d. Lung
d. Lung
Acoustic velocity is defined as the: Select one: a. Number of cycles per second b. Speed of the vibrating particles in the medium c. Inverse of the frequency d. Speed at which the sound wave propagates through a medium
d. Speed at which the sound wave propagates through a medium
Which of the following is a definition of period? Select one: a. Time it takes for the pulse to travel through the medium b. Distance it takes for one complete cycle to occur c. Distance it takes for the pulse to travel through the medium d. Time it takes for one complete cycle to occur
d. Time it takes for one complete cycle to occur
The direction of motion of a particle in a wave is perpendicular to the direction of propagation of the wave. What type of wave is this? Select one: a. Longitudinal b. Acoustic c. Mechanical d. Transverse
d. Transverse
What is the unit for power? Select one: a. Hertz b. Decibels c. W/cm2 d. Watt
d. Watt
What term describes the distance of one cycle for a wave? Select one: a. Acoustic velocity b. Frequency c. Period d. Wavelength
d. Wavelength
As the power of the beam increases, intensity will: Select one: a. Quadruple b. Decrease c. Double d. Increase
d. increase