Ultrasound Physics - Mock Exam Questions for
SPI with Complete Answers Key | New 2026-2027
Update
1. Which of the following transducers will have the worst axial resolution?
• A. Vector array, 3 MHz
• B. Linear Sequential Array, 6 MHz
• C. Linear Phased Array, 7.5 MHz
• D. Annular Array, 6 MHz
Correct Answer: A — Vector array, 3 MHz
Expert Rationale: Axial resolution improves with higher frequency and shorter
spatial pulse length. The lowest frequency listed (3 MHz) will have the longest
wavelength and therefore the worst axial resolution.
2. A sound wave is traveling in the body and propagates from muscle to air.
What percentage of the sound wave is most likely reflected at the muscle-air
boundary?
• A. 0.5%
• B. 75%
• C. 25%
• D. 5%
• E. 99%
Corrected Answer: E — 99%
,Expert Rationale: The acoustic impedance mismatch between soft tissue and air is
extremely large, so nearly all sound is reflected. Transmission is only about 0.1%–
0.5%. The source marked 75%, which is incorrect.
3. Which of the following lists is in decreasing order?
• A. mega, kilo, deca, milli, nano
• B. centi, milli, kilo, mega, nano
• C. micro, milli, deci, kilo, mega
• D. micro, kilo, mega, deci, milli
• E. mega, micro, deci, milli, hecto
Correct Answer: A — mega, kilo, deca, milli, nano
Expert Rationale: Decreasing order of metric prefixes: mega (10⁶) > kilo (10³) >
deca (10¹) > milli (10⁻³) > nano (10⁻⁹).
4. During a diagnostic exam, which of these statements is most correct when
describing the pulsed echo characteristics of an ultrasound system?
• A. The listening time may be one-thousand times longer than the pulse
duration.
• B. The pulse duration is longer than the pulse repetition period.
• C. The pulse duration is similar to the listening time.
• D. The duty factor has a value close to 1.
• E. The pulse repetition period is similar to the period.
Correct Answer: A — The listening time may be one-thousand times longer than
the pulse duration.
Expert Rationale: In pulsed ultrasound, the duty factor is typically ~0.1%–1%, so
listening time is much longer than pulse duration.
,5. Which of the following parameters is determined by both the ultrasound
system and the medium through which the sound travels?
• A. Period
• B. Frequency
• C. Temperature
• D. Wavelength
• E. Velocity of the sound
Correct Answer: D — Wavelength
Expert Rationale: Wavelength = propagation speed / frequency. Frequency is
determined by the source; propagation speed is determined by the medium.
Therefore, wavelength depends on both.
6. You should be familiar with the formula L = C/F. What does “C” stand for in
this equation?
• A. Characteristic impedance
• B. Density
• C. Compliance
• D. Compressibility
• E. Propagation speed
Correct Answer: E — Propagation speed
Expert Rationale: In λ = c/f, c is the speed of sound in the medium.
7. Which of the following lists is in increasing order?
• A. mega, kilo, milli, nano, centi
• B. centi, milli, kilo, mega, nano
, • C. micro, kilo, milli, deci, mega
• D. micro, milli, deci, kilo, mega
• E. mega, micro, deci, milli, hecto
Correct Answer: D — micro, milli, deci, kilo, mega
Expert Rationale: Increasing metric order: micro (10⁻⁶) < milli (10⁻³) < deci (10⁻¹) <
kilo (10³) < mega (10⁶).
8. Which of the following statements about speed and attenuation are true?
• A. Attenuation through and propagation speed in a particular medium are
unrelated to each other.
• B. When a sound beam travels faster in a medium, the attenuation is less.
• C. When a sound beam travels slower in a medium, the attenuation is more.
Correct Answer: A — Attenuation through and propagation speed in a particular
medium are unrelated to each other.
Expert Rationale: Attenuation depends on absorption and scattering; propagation
speed depends on stiffness and density. They are independent properties.
9. A sonographer is scanning a patient with a 3 MHz probe and replaces it with a
6 MHz probe. All of the following statements are FALSE, except:
• A. The 6 MHz beam will travel at a lower speed than the 3 MHz beam.
• B. The 6 MHz beam will travel faster than the 3 MHz beam.
• C. The 3 MHz beam will have a higher frequency than the 6 MHz beam.
• D. The 6 MHz beam will have a longer period than the 3 MHz beam.
• E. The 3 MHz beam will have a longer wavelength than the 6 MHz beam.
Correct Answer: E — The 3 MHz beam will have a longer wavelength than the 6
MHz beam.
SPI with Complete Answers Key | New 2026-2027
Update
1. Which of the following transducers will have the worst axial resolution?
• A. Vector array, 3 MHz
• B. Linear Sequential Array, 6 MHz
• C. Linear Phased Array, 7.5 MHz
• D. Annular Array, 6 MHz
Correct Answer: A — Vector array, 3 MHz
Expert Rationale: Axial resolution improves with higher frequency and shorter
spatial pulse length. The lowest frequency listed (3 MHz) will have the longest
wavelength and therefore the worst axial resolution.
2. A sound wave is traveling in the body and propagates from muscle to air.
What percentage of the sound wave is most likely reflected at the muscle-air
boundary?
• A. 0.5%
• B. 75%
• C. 25%
• D. 5%
• E. 99%
Corrected Answer: E — 99%
,Expert Rationale: The acoustic impedance mismatch between soft tissue and air is
extremely large, so nearly all sound is reflected. Transmission is only about 0.1%–
0.5%. The source marked 75%, which is incorrect.
3. Which of the following lists is in decreasing order?
• A. mega, kilo, deca, milli, nano
• B. centi, milli, kilo, mega, nano
• C. micro, milli, deci, kilo, mega
• D. micro, kilo, mega, deci, milli
• E. mega, micro, deci, milli, hecto
Correct Answer: A — mega, kilo, deca, milli, nano
Expert Rationale: Decreasing order of metric prefixes: mega (10⁶) > kilo (10³) >
deca (10¹) > milli (10⁻³) > nano (10⁻⁹).
4. During a diagnostic exam, which of these statements is most correct when
describing the pulsed echo characteristics of an ultrasound system?
• A. The listening time may be one-thousand times longer than the pulse
duration.
• B. The pulse duration is longer than the pulse repetition period.
• C. The pulse duration is similar to the listening time.
• D. The duty factor has a value close to 1.
• E. The pulse repetition period is similar to the period.
Correct Answer: A — The listening time may be one-thousand times longer than
the pulse duration.
Expert Rationale: In pulsed ultrasound, the duty factor is typically ~0.1%–1%, so
listening time is much longer than pulse duration.
,5. Which of the following parameters is determined by both the ultrasound
system and the medium through which the sound travels?
• A. Period
• B. Frequency
• C. Temperature
• D. Wavelength
• E. Velocity of the sound
Correct Answer: D — Wavelength
Expert Rationale: Wavelength = propagation speed / frequency. Frequency is
determined by the source; propagation speed is determined by the medium.
Therefore, wavelength depends on both.
6. You should be familiar with the formula L = C/F. What does “C” stand for in
this equation?
• A. Characteristic impedance
• B. Density
• C. Compliance
• D. Compressibility
• E. Propagation speed
Correct Answer: E — Propagation speed
Expert Rationale: In λ = c/f, c is the speed of sound in the medium.
7. Which of the following lists is in increasing order?
• A. mega, kilo, milli, nano, centi
• B. centi, milli, kilo, mega, nano
, • C. micro, kilo, milli, deci, mega
• D. micro, milli, deci, kilo, mega
• E. mega, micro, deci, milli, hecto
Correct Answer: D — micro, milli, deci, kilo, mega
Expert Rationale: Increasing metric order: micro (10⁻⁶) < milli (10⁻³) < deci (10⁻¹) <
kilo (10³) < mega (10⁶).
8. Which of the following statements about speed and attenuation are true?
• A. Attenuation through and propagation speed in a particular medium are
unrelated to each other.
• B. When a sound beam travels faster in a medium, the attenuation is less.
• C. When a sound beam travels slower in a medium, the attenuation is more.
Correct Answer: A — Attenuation through and propagation speed in a particular
medium are unrelated to each other.
Expert Rationale: Attenuation depends on absorption and scattering; propagation
speed depends on stiffness and density. They are independent properties.
9. A sonographer is scanning a patient with a 3 MHz probe and replaces it with a
6 MHz probe. All of the following statements are FALSE, except:
• A. The 6 MHz beam will travel at a lower speed than the 3 MHz beam.
• B. The 6 MHz beam will travel faster than the 3 MHz beam.
• C. The 3 MHz beam will have a higher frequency than the 6 MHz beam.
• D. The 6 MHz beam will have a longer period than the 3 MHz beam.
• E. The 3 MHz beam will have a longer wavelength than the 6 MHz beam.
Correct Answer: E — The 3 MHz beam will have a longer wavelength than the 6
MHz beam.
