SPI Practice Test Questions and Answers Plus
Rationale | New 2026-2027 Update
1. Which of the following do the source and the medium determine?
A. Duty factor
B. Frequency
C. Propagation speed
D. Axial resolution
Correct Answer: D — Axial resolution
Rationale: Axial resolution depends on spatial pulse length, which is influenced
by the source (number of cycles) and the medium (propagation
speed/wavelength).
2. Axial resolution is affected by all of the following EXCEPT
A. Frequency
B. Damping
C. Spatial pulse length
D. Focusing
Correct Answer: D — Focusing
Rationale: Focusing primarily affects lateral resolution, not axial resolution.
3. Damping in a transducer
A. Reduces the number of cycles in a pulse and increases the quality factor
B. Increases the number of cycles in a pulse and increases penetration
C. Causes poor axial and lateral resolution
D. Reduces the duty factor and increases the range of transmitted frequencies
Correct Answer: D — Reduces the duty factor and increases the range of
transmitted frequencies
,Rationale: Damping shortens the pulse, broadens bandwidth, lowers Q, and can
reduce duty factor.
4. Far zone beam divergence can be reduced on a single-element transducer by
using
A. A transducer with a smaller element diameter
B. A higher frequency transducer
C. A lower frequency transducer or a smaller element diameter
D. Adjustable focusing
Correct Answer: B — A higher frequency transducer
Rationale: Divergence angle decreases with higher frequency and larger
diameter, not smaller diameter.
5. The area between the face of an unfocused single-element transducer and the
point where the beam starts to diverge is the
A. Fraunhofer zone
B. Refraction zone
C. Focal zone
D. Near zone
Correct Answer: D — Near zone
Rationale: The near zone (Fresnel zone) extends from the transducer face to the
natural focus.
6. Assuming a fixed frequency, what happens if the diameter of an unfocused
transducer is increased?
A. The far zone divergence increases
B. The penetration decreases
C. The length of the near zone increases
D. The length of the near zone decreases
Correct Answer: C — The length of the near zone increases
Rationale: Near zone length is proportional to diameter squared.
,7. Which of the following does NOT affect lateral resolution?
A. Focusing
B. Element diameter
C. Frequency
D. Bandwidth
Correct Answer: D — Bandwidth
Rationale: Bandwidth primarily affects axial resolution.
8. Higher frequency transducers provide
A. Improved lateral resolution
B. Smaller Doppler shifts
C. Improved axial resolution and reduced attenuation
D. Increased penetration
Correct Answer: A — Improved lateral resolution
Rationale: Higher frequency improves lateral and axial resolution but increases
attenuation and reduces penetration.
9. Ultrasound waves that are traveling through a medium consist of
A. Electromagnetic and radio frequencies
B. Compressions and refractions
C. Electromagnetic and ionizing frequencies
D. Compressions and rarefactions
Correct Answer: D — Compressions and rarefactions
Rationale: Sound is a mechanical longitudinal wave consisting of compressions
and rarefactions.
10. What is the difference between audible sound and ultrasound?
A. Audible sound waves can travel through a vacuum
B. Audible sound has a higher frequency
, C. Ultrasound has a higher frequency
D. Ultrasound waves are ionizing
Correct Answer: C — Ultrasound has a higher frequency
Rationale: Ultrasound is >20,000 Hz; audible sound is 20–20,000 Hz.
11. A decrease in the thickness of a piezoelectric element will result in
A. A greater pulse duration
B. An increase in the propagation speed
C. A decrease in the quality factor if the bandwidth decreases
D. An increase in the frequency of the transducer
Correct Answer: D — An increase in the frequency of the transducer
Rationale: Frequency is inversely proportional to crystal thickness.
12. The resonant frequency of a pulsed-wave ultrasound transducer is
dependent on
A. Damping
B. The backing material
C. The thickness of the piezoelectric element and the speed of sound through the
piezoelectric element
D. The amplitude of the voltage applied to the piezoelectric element
Correct Answer: C — The thickness of the piezoelectric element and the speed
of sound through the piezoelectric element
Rationale: f = c / 2t.
13. The image is brighter at the level of the focal zone. Which of the following
controls is best to correct this?
A. Overall gain
B. TGC
C. Acoustic power
D. PRF
Rationale | New 2026-2027 Update
1. Which of the following do the source and the medium determine?
A. Duty factor
B. Frequency
C. Propagation speed
D. Axial resolution
Correct Answer: D — Axial resolution
Rationale: Axial resolution depends on spatial pulse length, which is influenced
by the source (number of cycles) and the medium (propagation
speed/wavelength).
2. Axial resolution is affected by all of the following EXCEPT
A. Frequency
B. Damping
C. Spatial pulse length
D. Focusing
Correct Answer: D — Focusing
Rationale: Focusing primarily affects lateral resolution, not axial resolution.
3. Damping in a transducer
A. Reduces the number of cycles in a pulse and increases the quality factor
B. Increases the number of cycles in a pulse and increases penetration
C. Causes poor axial and lateral resolution
D. Reduces the duty factor and increases the range of transmitted frequencies
Correct Answer: D — Reduces the duty factor and increases the range of
transmitted frequencies
,Rationale: Damping shortens the pulse, broadens bandwidth, lowers Q, and can
reduce duty factor.
4. Far zone beam divergence can be reduced on a single-element transducer by
using
A. A transducer with a smaller element diameter
B. A higher frequency transducer
C. A lower frequency transducer or a smaller element diameter
D. Adjustable focusing
Correct Answer: B — A higher frequency transducer
Rationale: Divergence angle decreases with higher frequency and larger
diameter, not smaller diameter.
5. The area between the face of an unfocused single-element transducer and the
point where the beam starts to diverge is the
A. Fraunhofer zone
B. Refraction zone
C. Focal zone
D. Near zone
Correct Answer: D — Near zone
Rationale: The near zone (Fresnel zone) extends from the transducer face to the
natural focus.
6. Assuming a fixed frequency, what happens if the diameter of an unfocused
transducer is increased?
A. The far zone divergence increases
B. The penetration decreases
C. The length of the near zone increases
D. The length of the near zone decreases
Correct Answer: C — The length of the near zone increases
Rationale: Near zone length is proportional to diameter squared.
,7. Which of the following does NOT affect lateral resolution?
A. Focusing
B. Element diameter
C. Frequency
D. Bandwidth
Correct Answer: D — Bandwidth
Rationale: Bandwidth primarily affects axial resolution.
8. Higher frequency transducers provide
A. Improved lateral resolution
B. Smaller Doppler shifts
C. Improved axial resolution and reduced attenuation
D. Increased penetration
Correct Answer: A — Improved lateral resolution
Rationale: Higher frequency improves lateral and axial resolution but increases
attenuation and reduces penetration.
9. Ultrasound waves that are traveling through a medium consist of
A. Electromagnetic and radio frequencies
B. Compressions and refractions
C. Electromagnetic and ionizing frequencies
D. Compressions and rarefactions
Correct Answer: D — Compressions and rarefactions
Rationale: Sound is a mechanical longitudinal wave consisting of compressions
and rarefactions.
10. What is the difference between audible sound and ultrasound?
A. Audible sound waves can travel through a vacuum
B. Audible sound has a higher frequency
, C. Ultrasound has a higher frequency
D. Ultrasound waves are ionizing
Correct Answer: C — Ultrasound has a higher frequency
Rationale: Ultrasound is >20,000 Hz; audible sound is 20–20,000 Hz.
11. A decrease in the thickness of a piezoelectric element will result in
A. A greater pulse duration
B. An increase in the propagation speed
C. A decrease in the quality factor if the bandwidth decreases
D. An increase in the frequency of the transducer
Correct Answer: D — An increase in the frequency of the transducer
Rationale: Frequency is inversely proportional to crystal thickness.
12. The resonant frequency of a pulsed-wave ultrasound transducer is
dependent on
A. Damping
B. The backing material
C. The thickness of the piezoelectric element and the speed of sound through the
piezoelectric element
D. The amplitude of the voltage applied to the piezoelectric element
Correct Answer: C — The thickness of the piezoelectric element and the speed
of sound through the piezoelectric element
Rationale: f = c / 2t.
13. The image is brighter at the level of the focal zone. Which of the following
controls is best to correct this?
A. Overall gain
B. TGC
C. Acoustic power
D. PRF
