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