SPI Practice Test | 500 Questions with Correct
Answer plus Rationale | Latest 2026-2027 Update
1. A sound wave is:
A. transverse
B. electromagnetic
C. mechanical, longitudinal
D. transverse, longitudinal
Correct Answer: C. mechanical, longitudinal
Rationale: Sound is a mechanical pressure wave that propagates through a
medium via longitudinal particle motion (compressions and rarefactions). It is not
electromagnetic and not transverse.
2. A compression area of a sound wave is:
A. high pressure, low density
B. low pressure, low density
C. high pressure, high density
D. low pressure, high density
Correct Answer: C. high pressure, high density
Rationale: In a compression, particles are crowded together, increasing both
pressure and density.
3. A rarefaction area of a sound wave is:
A. high pressure, low density
B. low pressure, low density
C. high pressure, high density
D. low pressure, high density
,Correct Answer: B. low pressure, low density
Rationale: In a rarefaction, particles are spread apart, decreasing both pressure
and density.
4. Which of the following is considered an acoustic variable?
A. power
B. intensity
C. amplitude
D. pressure
Correct Answer: D. pressure
Rationale: Pressure is an acoustic variable. Power, intensity, and amplitude are
derived quantities.
5. Which of the following is a unit for pressure?
A. lbs/in
B. N/m²
C. kg/cm³
D. inches²
Correct Answer: B. N/m²
Rationale: The Pascal (N/m²) is the SI unit of pressure.
6. Which of the following is a correct unit for density?
A. lb/in
B. mm Hg
C. centigrade
D. lbs/cm³
Correct Answer: D. lbs/cm³
Rationale: Density is mass per unit volume; lbs/cm³ is a valid density unit.
,7. Which of the following waves propagate in medium?
A. heat
B. light
C. x-ray
D. sound
Correct Answer: D. sound
Rationale: Sound requires a medium; light, heat, and X-rays can propagate
through a vacuum.
8. The range for ultrasound is:
A. less than 20 Hz
B. 20 Hz to 20,000 Hz
C. greater than 20 kHz
D. 2 MHz to 10 MHz
Correct Answer: C. greater than 20 kHz
Rationale: Ultrasound is defined as sound >20,000 Hz (20 kHz).
9. ______________ is the number of wave cycles per second.
A. frequency
B. period
C. wavelength
D. amplitude
Correct Answer: A. frequency
Rationale: Frequency is cycles per second, measured in Hertz.
10. One kilohertz is equal to:
, A. one cycle per second
B. 100 cycles per second
C. 1,000 cycles per second
D. 10,000 cycles per second
Correct Answer: C. 1,000 cycles per second
Rationale: 1 kHz = 1,000 Hz.
11. One Megahertz is equal to:
A. one cycle per second
B. one hundred cycles per second
C. one thousand cycles per second
D. one million cycles per second
Correct Answer: D. one million cycles per second
Rationale: 1 MHz = 1,000,000 Hz.
12. The useful frequency range for clinical imaging ultrasound is:
A. 20 Hz
B. 20 Hz to 20 kHz
C. 1 Hz to 10 kHz
D. 2 MHz to 10 MHz
Correct Answer: D. 2 MHz to 10 MHz
Rationale: Clinical imaging typically uses 2–10 MHz; higher frequencies for
superficial structures, lower for deep.
13. Frequency is determined by the:
A. source
B. medium
Answer plus Rationale | Latest 2026-2027 Update
1. A sound wave is:
A. transverse
B. electromagnetic
C. mechanical, longitudinal
D. transverse, longitudinal
Correct Answer: C. mechanical, longitudinal
Rationale: Sound is a mechanical pressure wave that propagates through a
medium via longitudinal particle motion (compressions and rarefactions). It is not
electromagnetic and not transverse.
2. A compression area of a sound wave is:
A. high pressure, low density
B. low pressure, low density
C. high pressure, high density
D. low pressure, high density
Correct Answer: C. high pressure, high density
Rationale: In a compression, particles are crowded together, increasing both
pressure and density.
3. A rarefaction area of a sound wave is:
A. high pressure, low density
B. low pressure, low density
C. high pressure, high density
D. low pressure, high density
,Correct Answer: B. low pressure, low density
Rationale: In a rarefaction, particles are spread apart, decreasing both pressure
and density.
4. Which of the following is considered an acoustic variable?
A. power
B. intensity
C. amplitude
D. pressure
Correct Answer: D. pressure
Rationale: Pressure is an acoustic variable. Power, intensity, and amplitude are
derived quantities.
5. Which of the following is a unit for pressure?
A. lbs/in
B. N/m²
C. kg/cm³
D. inches²
Correct Answer: B. N/m²
Rationale: The Pascal (N/m²) is the SI unit of pressure.
6. Which of the following is a correct unit for density?
A. lb/in
B. mm Hg
C. centigrade
D. lbs/cm³
Correct Answer: D. lbs/cm³
Rationale: Density is mass per unit volume; lbs/cm³ is a valid density unit.
,7. Which of the following waves propagate in medium?
A. heat
B. light
C. x-ray
D. sound
Correct Answer: D. sound
Rationale: Sound requires a medium; light, heat, and X-rays can propagate
through a vacuum.
8. The range for ultrasound is:
A. less than 20 Hz
B. 20 Hz to 20,000 Hz
C. greater than 20 kHz
D. 2 MHz to 10 MHz
Correct Answer: C. greater than 20 kHz
Rationale: Ultrasound is defined as sound >20,000 Hz (20 kHz).
9. ______________ is the number of wave cycles per second.
A. frequency
B. period
C. wavelength
D. amplitude
Correct Answer: A. frequency
Rationale: Frequency is cycles per second, measured in Hertz.
10. One kilohertz is equal to:
, A. one cycle per second
B. 100 cycles per second
C. 1,000 cycles per second
D. 10,000 cycles per second
Correct Answer: C. 1,000 cycles per second
Rationale: 1 kHz = 1,000 Hz.
11. One Megahertz is equal to:
A. one cycle per second
B. one hundred cycles per second
C. one thousand cycles per second
D. one million cycles per second
Correct Answer: D. one million cycles per second
Rationale: 1 MHz = 1,000,000 Hz.
12. The useful frequency range for clinical imaging ultrasound is:
A. 20 Hz
B. 20 Hz to 20 kHz
C. 1 Hz to 10 kHz
D. 2 MHz to 10 MHz
Correct Answer: D. 2 MHz to 10 MHz
Rationale: Clinical imaging typically uses 2–10 MHz; higher frequencies for
superficial structures, lower for deep.
13. Frequency is determined by the:
A. source
B. medium
