ARDMS SPI Exam 2026/2027 | Sonography Principles &
Instrumentation | Complete Practice Questions, Correct
Answers & Detailed Rationales
SECTION 1 — PERFORM ULTRASOUND EXAMINATIONS & PHYSICAL PRINCIPLES
Questions 1–69
1. Which acoustic parameter describes the number of complete cycles occurring
per second?
A. Period
B. Frequency
C. Wavelength
D. Amplitude
Correct Answer: B. Frequency
Rationale: Frequency is the number of cycles occurring per second and is
measured in hertz.
2. What is the SI unit for frequency?
A. Meter
B. Pascal
C. Hertz
D. Watt
Correct Answer: C. Hertz
Rationale: Frequency is measured in hertz (Hz), with 1 Hz equal to one cycle per
second.
3. If the frequency of sound increases while propagation speed remains
constant, wavelength will:
,A. Increase
B. Decrease
C. Remain unchanged
D. Become zero
Correct Answer: B. Decrease
Rationale: Wavelength equals propagation speed divided by frequency. Increasing
frequency therefore decreases wavelength.
4. Which equation correctly relates propagation speed, frequency, and
wavelength?
A. c = fλ
B. c = f/λ
C. λ = cf
D. f = cλ
Correct Answer: A. c = fλ
Rationale: Propagation speed equals frequency multiplied by wavelength.
5. What determines the propagation speed of ultrasound in soft tissue?
A. Frequency only
B. Amplitude only
C. Medium properties
D. Transducer diameter only
Correct Answer: C. Medium properties
Rationale: Propagation speed depends primarily on the stiffness and density of
the medium.
6. The average assumed propagation speed used by most diagnostic ultrasound
systems for soft tissue is approximately:
A. 330 m/s
,B. 1,540 m/s
C. 3,080 m/s
D. 154 m/s
Correct Answer: B. 1,540 m/s
Rationale: Ultrasound systems generally assume an average soft-tissue
propagation speed of approximately 1,540 m/s.
7. Which acoustic variable is most directly related to the strength of a sound
wave?
A. Amplitude
B. Period
C. Frequency
D. Wavelength
Correct Answer: A. Amplitude
Rationale: Amplitude represents the maximum variation from the undisturbed
state and is related to wave strength.
8. What is the time required for one complete cycle called?
A. Frequency
B. Period
C. Intensity
D. Duty factor
Correct Answer: B. Period
Rationale: Period is the time required for one complete acoustic cycle.
9. If frequency is 5 MHz, the period is:
A. 0.2 μs
B. 2 μs
, C. 5 μs
D. 20 μs
Correct Answer: A. 0.2 μs
Rationale: Period = 1/frequency = 1/(5,000,000) seconds = 0.2 microseconds.
10. Which characteristic distinguishes ultrasound from audible sound?
A. Ultrasound has no wavelength
B. Ultrasound has frequencies above human hearing
C. Ultrasound cannot propagate through tissue
D. Ultrasound travels only through air
Correct Answer: B. Ultrasound has frequencies above human hearing
Rationale: Ultrasound refers to sound above approximately 20 kHz, while
diagnostic ultrasound typically uses frequencies in the MHz range.
11. Acoustic impedance is determined by:
A. Density × propagation speed
B. Frequency × wavelength
C. Amplitude × period
D. Intensity × frequency
Correct Answer: A. Density × propagation speed
Rationale: Acoustic impedance is Z = ρc, where ρ is density and c is propagation
speed.
12. Which tissue interface produces the strongest reflection?
A. Two tissues with nearly identical impedances
B. Two tissues with a large impedance mismatch
C. Two tissues with identical densities
D. Two tissues with identical propagation speeds
Instrumentation | Complete Practice Questions, Correct
Answers & Detailed Rationales
SECTION 1 — PERFORM ULTRASOUND EXAMINATIONS & PHYSICAL PRINCIPLES
Questions 1–69
1. Which acoustic parameter describes the number of complete cycles occurring
per second?
A. Period
B. Frequency
C. Wavelength
D. Amplitude
Correct Answer: B. Frequency
Rationale: Frequency is the number of cycles occurring per second and is
measured in hertz.
2. What is the SI unit for frequency?
A. Meter
B. Pascal
C. Hertz
D. Watt
Correct Answer: C. Hertz
Rationale: Frequency is measured in hertz (Hz), with 1 Hz equal to one cycle per
second.
3. If the frequency of sound increases while propagation speed remains
constant, wavelength will:
,A. Increase
B. Decrease
C. Remain unchanged
D. Become zero
Correct Answer: B. Decrease
Rationale: Wavelength equals propagation speed divided by frequency. Increasing
frequency therefore decreases wavelength.
4. Which equation correctly relates propagation speed, frequency, and
wavelength?
A. c = fλ
B. c = f/λ
C. λ = cf
D. f = cλ
Correct Answer: A. c = fλ
Rationale: Propagation speed equals frequency multiplied by wavelength.
5. What determines the propagation speed of ultrasound in soft tissue?
A. Frequency only
B. Amplitude only
C. Medium properties
D. Transducer diameter only
Correct Answer: C. Medium properties
Rationale: Propagation speed depends primarily on the stiffness and density of
the medium.
6. The average assumed propagation speed used by most diagnostic ultrasound
systems for soft tissue is approximately:
A. 330 m/s
,B. 1,540 m/s
C. 3,080 m/s
D. 154 m/s
Correct Answer: B. 1,540 m/s
Rationale: Ultrasound systems generally assume an average soft-tissue
propagation speed of approximately 1,540 m/s.
7. Which acoustic variable is most directly related to the strength of a sound
wave?
A. Amplitude
B. Period
C. Frequency
D. Wavelength
Correct Answer: A. Amplitude
Rationale: Amplitude represents the maximum variation from the undisturbed
state and is related to wave strength.
8. What is the time required for one complete cycle called?
A. Frequency
B. Period
C. Intensity
D. Duty factor
Correct Answer: B. Period
Rationale: Period is the time required for one complete acoustic cycle.
9. If frequency is 5 MHz, the period is:
A. 0.2 μs
B. 2 μs
, C. 5 μs
D. 20 μs
Correct Answer: A. 0.2 μs
Rationale: Period = 1/frequency = 1/(5,000,000) seconds = 0.2 microseconds.
10. Which characteristic distinguishes ultrasound from audible sound?
A. Ultrasound has no wavelength
B. Ultrasound has frequencies above human hearing
C. Ultrasound cannot propagate through tissue
D. Ultrasound travels only through air
Correct Answer: B. Ultrasound has frequencies above human hearing
Rationale: Ultrasound refers to sound above approximately 20 kHz, while
diagnostic ultrasound typically uses frequencies in the MHz range.
11. Acoustic impedance is determined by:
A. Density × propagation speed
B. Frequency × wavelength
C. Amplitude × period
D. Intensity × frequency
Correct Answer: A. Density × propagation speed
Rationale: Acoustic impedance is Z = ρc, where ρ is density and c is propagation
speed.
12. Which tissue interface produces the strongest reflection?
A. Two tissues with nearly identical impedances
B. Two tissues with a large impedance mismatch
C. Two tissues with identical densities
D. Two tissues with identical propagation speeds
