1.
Electromagnetic waves can exist in...
Correct Answer
C. Both
Explanation
Electromagnetic waves can exist in both a medium and a vacuum. In a medium, such as air or water, electromagnetic waves can travel by causing the atoms or molecules in the medium to vibrate. In a vacuum, electromagnetic waves can still propagate because they do not require a physical medium to travel through. This is because electromagnetic waves are composed of oscillating electric and magnetic fields, which can travel through empty space without the need for a material medium. Therefore, electromagnetic waves can exist in both a medium and a vacuum.
2.
Mechanical waves can exist in...
Correct Answer
A. Medium only
Explanation
Mechanical waves are waves that require a medium to propagate. They cannot travel through a vacuum because they rely on the particles of the medium to transfer energy. Therefore, the correct answer is "Medium only".
3.
Electromagnetic wave direction
Correct Answer(s)
A. Transverse
D. Perpendicular
Explanation
Electromagnetic waves are transverse waves, meaning that the oscillations of the electric and magnetic fields occur perpendicular to the direction of wave propagation. This is why the correct answer is "Transverse." Additionally, the electric and magnetic fields in an electromagnetic wave are also perpendicular to each other, which is why the correct answer is also "Perpendicular."
4.
Mechanical wave direction
Correct Answer(s)
B. Longitudinal
C. Parallel
Explanation
Mechanical waves can be classified into two main types: transverse and longitudinal. Transverse waves are characterized by the particles of the medium vibrating perpendicular to the direction of wave propagation. On the other hand, longitudinal waves are characterized by the particles of the medium vibrating parallel to the direction of wave propagation. Therefore, the correct answer is "Longitudinal, Parallel" as both terms describe the direction of the mechanical wave.
5.
Which of the following parameters is inconsequential to clinical ultrasound?
Correct Answer
B. Temperature
Explanation
Temperature is inconsequential to clinical ultrasound because it does not directly affect the performance or interpretation of ultrasound imaging. Unlike pressure, density, and particle motion, temperature does not impact the propagation of sound waves through tissues. The speed of sound in tissues is mainly determined by the density and elasticity of the medium, while temperature has a minimal effect on these properties. Therefore, variations in temperature within the normal range do not significantly affect the accuracy or quality of clinical ultrasound imaging.
6.
What occurs during compression?
Correct Answer
B. Increased pressure, increased density
Explanation
During compression, the pressure exerted on a substance increases, causing the molecules to be pushed closer together. This results in an increase in density, as the same amount of matter is now occupying a smaller volume. Therefore, the correct answer is "Increased pressure, increased density."
7.
What occurs during rarefaction?
Correct Answer
C. Decreased pressure, decreased density
Explanation
During rarefaction, the pressure of a medium decreases, which means that the particles in the medium are moving further apart. This results in a decrease in density because there are fewer particles in a given volume. Therefore, the correct answer is "Decreased pressure, decreased density."
8.
Period: units
Correct Answer
C. Microseconds
Explanation
The answer is microseconds because it is a unit of time that is smaller than seconds but larger than milliseconds. It is commonly used to measure very small durations of time, such as the delay between electronic signals or the response time of computer systems.
9.
Period: typical values
Correct Answer
A. .1-.5 µs
Explanation
The correct answer is .1-.5 µs. This range represents typical values for the period of a signal. A period is the time it takes for one complete cycle of a waveform to occur. In this case, the period of the signal is between 0.1 and 0.5 microseconds. This suggests that the signal repeats itself within this time frame, with a frequency that corresponds to this period.
10.
Period is determined by sound source only
Correct Answer
A. True
Explanation
The statement "Period is determined by sound source only" is true. The period of a sound wave refers to the time it takes for one complete cycle of the wave to occur. It is solely determined by the frequency of the sound source, which is the number of cycles per second. The sound source itself, such as a vibrating object or an instrument, determines the frequency and therefore the period of the sound wave it produces. Other factors like the medium through which the sound travels may affect the speed or intensity of the wave, but they do not directly impact the period.
11.
Period is not adjustable
Correct Answer
A. True
Explanation
The statement "Period is not adjustable" means that the period, which refers to a specific length of time, cannot be changed or modified. This implies that the period remains constant and cannot be altered according to any external factors or preferences. Therefore, the correct answer is "True" as it confirms that the period is indeed not adjustable.
12.
Frequency: units
Correct Answer
C. Hertz
Explanation
Hertz is a unit used to measure frequency, specifically the number of cycles or oscillations per second. Decibels measure the intensity or loudness of sound, watts measure power, and milliseconds measure time. Therefore, Hertz is the correct answer as it is the unit that specifically measures frequency.
13.
Frequency: Typical Values
Correct Answer
D. 2-10 MHz
Explanation
The given frequency range of 2-10 MHz is typically used for ultrasound imaging. This range is suitable for medical applications as it allows for better resolution and imaging of soft tissues. Higher frequencies provide finer detail and better resolution, which is important for visualizing small structures and detecting abnormalities. In contrast, lower frequencies are used for deeper penetration and imaging larger structures. Therefore, the frequency range of 2-10 MHz is commonly used in medical ultrasound imaging for its ability to provide good resolution and depth penetration.
14.
Which of the following can be determined by medium?
Correct Answer(s)
C. Wavelength
G. Propagation Speed
Explanation
Medium can determine the wavelength because it affects how the waves interact with the medium. Different mediums have different properties that can cause the wavelength to change. Additionally, the propagation speed can also be determined by the medium. The properties of the medium, such as its density and elasticity, can affect how fast the waves propagate through it. Therefore, both wavelength and propagation speed can be influenced by the medium.
15.
Which of the following are adjustable by the sonographer?
Correct Answer(s)
A. Intensity
C. Power
G. Amplitude
Explanation
The sonographer is able to adjust the intensity, power, and amplitude during an ultrasound examination. Intensity refers to the strength or power of the ultrasound beam, which can be adjusted to control the level of energy delivered to the body. Power is the rate at which energy is delivered, and the sonographer can adjust it to control the strength of the ultrasound beam. Amplitude refers to the maximum displacement of a wave from its equilibrium position, and the sonographer can adjust it to control the strength of the ultrasound signal.
16.
Wavelength: Units
Correct Answer
A. Millimeters
Explanation
The given answer "Millimeters" is the correct unit for wavelength. Wavelength is a measure of the distance between two consecutive points in a wave, typically measured in meters or its subunits. Millimeters is a subunit of meters and is commonly used to measure small distances. Therefore, millimeters is an appropriate unit to measure the wavelength of a wave.
17.
Wavelength: Typical Values
Correct Answer
A. .15-.8 mm
Explanation
The correct answer is .15-.8 mm. This range represents the typical values for wavelength. Wavelength is the distance between two consecutive points in a wave that are in phase. The given range (.15-.8 mm) falls within the typical range of wavelengths for various types of waves, such as radio waves, microwaves, and infrared waves.
18.
Propagation Speed: Units
Correct Answer
D. Ms/s
Explanation
The correct answer is "ms/s" because it represents the units for propagation speed, which is the rate at which a wave travels through a medium. The abbreviation "ms/s" stands for meters per second, indicating that the wave travels a certain distance in meters within one second. This unit is commonly used to measure the speed of sound or electromagnetic waves.
19.
Propagation speed of air?
Correct Answer
D. 330
Explanation
The propagation speed of air refers to the speed at which sound waves travel through air. In this case, the correct answer is 330, which is likely referring to the speed of sound in meters per second at standard temperature and pressure. This value is commonly used as an approximation for the speed of sound in air.
20.
Propagation speed of soft tissue?
Correct Answer
A. 1540
Explanation
The correct answer is 1540. This refers to the propagation speed of sound waves in soft tissue. Sound travels at different speeds through different materials, and in soft tissue, such as muscles or organs, the speed is approximately 1540 meters per second. This speed is important in medical imaging techniques such as ultrasound, where sound waves are used to create images of internal structures. By knowing the propagation speed, accurate measurements and imaging can be achieved.
21.
Propagation speed of bone?
Correct Answer
D. 4000
Explanation
The correct answer is 4000. Bone has a propagation speed of 4000. This means that sound waves travel through bone at a speed of 4000 meters per second.
22.
Amplitude: Units
Correct Answer
B. Decibels
Explanation
Decibels are a unit used to measure the intensity or power level of sound. It is a logarithmic scale that compares the sound pressure level to a reference level. Decibels are commonly used in acoustics and audio engineering to express the loudness or volume of sound. It is not a unit of amplitude, which typically refers to the maximum displacement or variation in a wave. Pascals are the units for measuring pressure, watts for power, and hertz for frequency.
23.
Amplitude: Typical Values
Correct Answer
C. 1-3 MPa
Explanation
The correct answer is 1-3 MPa. The amplitude is a measure of the maximum displacement or distance from the equilibrium position in a wave. In this context, it refers to the maximum pressure variation in a sound wave. The given range of 1-3 MPa represents the typical values for the amplitude of sound waves, indicating the pressure fluctuations can range from 1 to 3 million pascals.
24.
Power: Units
Correct Answer
B. Milliwatts
Explanation
Milliwatts is the correct answer because it is a unit of power that is smaller than watts and is equal to one thousandth of a watt. In the given list of units, watts and milliwatts are both commonly used units to measure power. Watts/cm³ and megawatts are not commonly used units for power measurement.
25.
Power: Typical Values
Correct Answer
B. 4-90 mW
Explanation
The given answer, 4-90 mW, represents the typical values for power. Power is measured in milliwatts (mW), and the range of 4-90 mW indicates the expected power levels for a certain application or device. This range suggests that the power consumption or output of the device falls within this range, which is considered typical or normal.
26.
Intensity: Units
Correct Answer
C. Watts/cm²
Explanation
The correct answer is "Watts/cm²" because intensity is a measure of power per unit area. Watts is the unit of power, and cm² is the unit of area. Therefore, when measuring intensity, the unit is expressed as watts per square centimeter (Watts/cm²) to indicate the amount of power distributed over a specific area.
27.
Intensity: Typical Values
Correct Answer
C. .01- 300 W/cm²
Explanation
The given answer range of .01- 300 W/cm² falls within the typical values of intensity. It is common for intensity to range from very low values, such as .01 W/cm², to much higher values, such as 300 W/cm². Therefore, the given answer is a valid representation of the typical values of intensity.
28.
Frequency & Period
Correct Answer
A. Inversely
Explanation
The relationship between frequency and period is inverse. This means that as the frequency of a wave increases, the period decreases, and vice versa. Frequency refers to the number of complete cycles of a wave that occur in a given time, while period is the time it takes for one complete cycle to occur. As the frequency increases, the time it takes for each cycle to occur decreases, resulting in a shorter period. Conversely, if the frequency decreases, the period becomes longer.
29.
Amplitude & Power
Correct Answer
B. Directly
Explanation
The correct answer is "Directly" because when two variables are said to be directly related, it means that as one variable increases, the other variable also increases. In this context, when we talk about amplitude and power, an increase in amplitude will result in an increase in power. Therefore, amplitude and power are directly related.
30.
Amplitude & Intensity
Correct Answer
B. Directly
Explanation
The correct answer is "Directly." This means that there is a direct relationship between amplitude and intensity. As the amplitude increases, the intensity also increases. Similarly, as the amplitude decreases, the intensity also decreases.
31.
Power & Intensity
Correct Answer
B. Directly
Explanation
The correct answer is "Directly." This suggests that there is a direct relationship between power and intensity. In other words, as power increases, intensity also increases. This implies that the two variables are positively correlated, meaning that when one variable increases, the other variable also increases.
32.
Wavelength & Intensity
Correct Answer
C. None
Explanation
The given answer "None" suggests that there is no relationship between wavelength and intensity. This means that as the wavelength of a wave changes, the intensity does not change in a predictable or consistent manner. In other words, the two variables are independent of each other and do not affect each other.
33.
Acoustic velocity & Density
Correct Answer
A. Inversely
Explanation
The given correct answer, "Inversely," suggests that there is an inverse relationship between acoustic velocity and density. This means that as one variable increases, the other variable decreases, and vice versa. In other words, when the density of a medium increases, the acoustic velocity decreases, and when the density decreases, the acoustic velocity increases. This relationship is important in understanding how sound waves travel through different materials, as the density of a medium affects the speed at which sound can propagate through it.
34.
Wavelength & Frequency
Correct Answer
A. Inversely
Explanation
The relationship between wavelength and frequency is inversely proportional. This means that as the wavelength increases, the frequency decreases, and vice versa. This can be explained by the wave equation, which states that the speed of a wave is equal to the product of its wavelength and frequency. Since the speed of a wave is constant, if one variable increases, the other must decrease to maintain the same speed. Therefore, wavelength and frequency have an inverse relationship.
35.
Elasticity & Speed of Sound
Correct Answer
B. Inversely
Explanation
The relationship between elasticity and speed of sound is inversely proportional. This means that as the elasticity of a medium increases, the speed of sound in that medium decreases, and vice versa. Elasticity refers to the ability of a material to deform under stress and then return to its original shape when the stress is removed. In the context of sound waves, a more elastic medium will allow the sound waves to propagate faster, while a less elastic medium will slow down the speed of sound. Therefore, the two variables are inversely related.
36.
Acoustic velocity & Compressibility
Correct Answer
A. Inversely
Explanation
The relationship between acoustic velocity and compressibility is that they are inversely proportional. This means that as the compressibility of a medium increases, the acoustic velocity decreases, and vice versa. In other words, when a medium is more compressible, it takes more time for sound waves to travel through it, resulting in a lower acoustic velocity. Conversely, when a medium is less compressible, sound waves can travel through it more quickly, resulting in a higher acoustic velocity.
37.
Stiffness & Speed of Sound
Correct Answer
B. Directly
Explanation
The correct answer is "Directly" because stiffness and speed of sound are directly related. This means that as the stiffness of a material increases, the speed of sound through that material also increases. Similarly, if the stiffness decreases, the speed of sound will also decrease. Therefore, there is a direct correlation between the two variables.
38.
Frequency & Speed of Sound
Correct Answer
A. None
Explanation
The answer "None" is correct because there is no relationship between frequency and speed of sound. They are two independent variables that are not affected by each other. The frequency of sound refers to the number of vibrations or cycles per second, while the speed of sound is the rate at which sound waves travel through a medium. Therefore, there is no direct or inverse relationship between the two.
39.
Frequency & Intensity
Correct Answer
B. None
Explanation
The given answer "None" suggests that there is no relationship between frequency and intensity. In other words, the two variables are not connected or influenced by each other. This means that as the frequency increases or decreases, the intensity does not change, and vice versa.
40.
Power & Frequency
Correct Answer
A. None
Explanation
The relationship between power and frequency is described as "None" in this context. This means that there is no direct or inverse relationship between power and frequency. The two variables are independent of each other and do not affect one another.
41.
Period & Frequency
Correct Answer
A. Inversely
Explanation
The term "inversely" suggests that there is a relationship between period and frequency where one increases while the other decreases. In the context of waves or oscillations, period refers to the time it takes for one complete cycle, while frequency represents the number of cycles that occur in a given time. Since these two quantities are inversely related, as the period increases, the frequency decreases, and vice versa.
42.
Wavelength & Speed
Correct Answer
C. Inversely
Explanation
The relationship between wavelength and speed is inversely proportional. This means that as the wavelength of a wave increases, the speed of the wave decreases, and vice versa. This can be observed in various types of waves, such as light waves and sound waves. For example, in a sound wave, if the wavelength increases, the speed of sound decreases, resulting in a lower pitch. Similarly, in a light wave, if the wavelength increases, the speed of light decreases, resulting in a shift towards the red end of the visible spectrum.
43.
Frequency & Wavelength
Correct Answer
A. Direct
Explanation
The relationship between frequency and wavelength is direct. This means that as the frequency of a wave increases, its wavelength also increases, and vice versa. In other words, when the frequency of a wave increases, the distance between two consecutive peaks or troughs decreases, resulting in a shorter wavelength. Conversely, when the frequency decreases, the distance between peaks or troughs increases, resulting in a longer wavelength. This direct relationship is a fundamental property of waves and is described by the wave equation, which states that the speed of a wave is equal to the product of its frequency and wavelength.
44.
Power= A ³
Correct Answer
B. False
Explanation
The given statement is false because the formula for power is not A cubed. The correct formula for power is P = A^2, where A represents the amplitude of the wave. Therefore, the correct answer is False.
45.
An increase in amplitude results in an decrease in intensity
Correct Answer
A. True
Explanation
When the amplitude of a wave increases, it means that the wave is becoming taller or more intense. However, the intensity of a wave is directly proportional to the square of its amplitude. This means that as the amplitude increases, the intensity decreases. Therefore, the statement that an increase in amplitude results in a decrease in intensity is true.
46.
Acceptable equations for solving for amplitude
Correct Answer(s)
B. Mean-Min
C. Mean-Max
E. Max+Min/2
Explanation
The given acceptable equations for solving for amplitude are Mean-Min, Mean-Max, and Max+Min/2. These equations involve calculating the difference between the mean and either the minimum or maximum values, or finding the average of the maximum and minimum values. These equations provide different ways to measure the range or spread of a dataset, which can be used to determine the amplitude.
47.
Density and Speed
Correct Answer
B. Increased Density= Decreased speed
Explanation
When the density of an object or substance increases, its speed decreases. This is because an increase in density means that there are more particles packed closely together, resulting in more collisions and interactions between the particles. These collisions and interactions create resistance and friction, which slows down the movement of the object or substance. Therefore, when density increases, the speed decreases.
48.
Stiffness and Speed
Correct Answer
A. Increase stiffness= Increased speed
Explanation
Increasing stiffness in a system leads to increased speed because stiffness refers to the resistance of an object to deformation. When an object is stiffer, it can withstand greater forces without deforming, allowing it to move faster. This is because the increased stiffness provides a stronger and more stable structure, enabling quicker and more efficient motion. On the other hand, if stiffness is decreased, the object becomes more flexible and prone to deformation, resulting in decreased speed.
49.
The loss of energy in sound waves occuring during propagation through medium, resulting in waves losing distance, frequency, and amplitude.
Correct Answer
B. Attenuation
Explanation
Attenuation is the correct answer because it refers to the loss of energy in sound waves during propagation through a medium. This loss of energy causes the waves to lose distance, frequency, and amplitude. Attenuation can occur due to factors such as absorption, scattering, and dispersion. It is an important phenomenon to consider in various applications of sound, such as in telecommunications and underwater acoustics.
50.
Which is the dominant form of attenuation?
Correct Answer
D. Absorption
Explanation
Absorption is the dominant form of attenuation because it refers to the process where energy of a wave is absorbed by the medium through which it is passing. This results in a decrease in the intensity of the wave. Unlike reflection, refraction, and scattering, which involve the redirection or dispersion of the wave, absorption involves the conversion of the wave's energy into other forms, such as heat. Therefore, absorption is the primary mechanism by which the intensity of a wave diminishes as it travels through a medium.