Davies Ultrasound Physics TEST STUDY GUIDE
2025/2026 ACCURATE QUESTIONS AND VERIFIED
CORRECT SOLUTIONS WITH RATIONALES || 100%
GUARANTEED PASS
Chapter 1: Basic Principles & Propagation
1. What is the definition of ultrasound?
• Answer: Sound with a frequency greater than 20,000 Hz (20 kHz), which is
beyond the range of human hearing.
• Rationale: This is the fundamental definition that distinguishes medical
ultrasound (typically 2-15 MHz) from audible sound.
2. What are the seven acoustic parameters? Describe them.
• Answer:
1. Period: Time to complete one cycle.
2. Frequency: Number of cycles per second (Hz). Determined by the
sound source.
3. Amplitude: The strength or magnitude of a wave (peak to middle).
4. Power: The rate at which work is done or energy is transferred.
5. Intensity: The concentration of power in a beam (Power/Area).
6. Wavelength: The length of one complete cycle in a medium.
7. Propagation Speed: The rate at which a sound wave travels through a
medium (e.g., ~1540 m/s in soft tissue).
• Rationale: These are the foundational building blocks of ultrasound physics.
Understanding their relationships (e.g., speed = frequency × wavelength) is
critical.
, 3. What is the relationship between frequency, penetration, and image
resolution?
• Answer:
o Higher Frequency: Shallow Penetration, but Better Axial
Resolution.
o Lower Frequency: Deeper Penetration, but Poorer Axial
Resolution.
• Rationale: Attenuation (weakening of the sound beam) increases with
frequency. However, axial resolution is directly proportional to the spatial
pulse length, which is shorter for higher frequencies.
4. What is the average propagation speed for sound in soft tissue?
• Answer: 1,540 meters per second (m/s).
• Rationale: This is the assumed and programmed speed in all clinical
ultrasound systems. It is an average for most body tissues, though individual
tissues vary (e.g., lung is much lower, bone is higher).
Chapter 2: Transducers & Pulse-Echo Principle
5. What is the Piezoelectric Effect?
• Answer: The property of certain materials (like PZT in the transducer) to
generate an electric voltage when subjected to mechanical pressure
(Receive), and conversely, to vibrate and produce sound waves when an
electric voltage is applied (Transmit).
• Rationale: This is the core principle that allows a single transducer element
to both create and receive ultrasound waves.
6. What is the difference between continuous wave and pulsed wave
ultrasound?
• Answer:
2025/2026 ACCURATE QUESTIONS AND VERIFIED
CORRECT SOLUTIONS WITH RATIONALES || 100%
GUARANTEED PASS
Chapter 1: Basic Principles & Propagation
1. What is the definition of ultrasound?
• Answer: Sound with a frequency greater than 20,000 Hz (20 kHz), which is
beyond the range of human hearing.
• Rationale: This is the fundamental definition that distinguishes medical
ultrasound (typically 2-15 MHz) from audible sound.
2. What are the seven acoustic parameters? Describe them.
• Answer:
1. Period: Time to complete one cycle.
2. Frequency: Number of cycles per second (Hz). Determined by the
sound source.
3. Amplitude: The strength or magnitude of a wave (peak to middle).
4. Power: The rate at which work is done or energy is transferred.
5. Intensity: The concentration of power in a beam (Power/Area).
6. Wavelength: The length of one complete cycle in a medium.
7. Propagation Speed: The rate at which a sound wave travels through a
medium (e.g., ~1540 m/s in soft tissue).
• Rationale: These are the foundational building blocks of ultrasound physics.
Understanding their relationships (e.g., speed = frequency × wavelength) is
critical.
, 3. What is the relationship between frequency, penetration, and image
resolution?
• Answer:
o Higher Frequency: Shallow Penetration, but Better Axial
Resolution.
o Lower Frequency: Deeper Penetration, but Poorer Axial
Resolution.
• Rationale: Attenuation (weakening of the sound beam) increases with
frequency. However, axial resolution is directly proportional to the spatial
pulse length, which is shorter for higher frequencies.
4. What is the average propagation speed for sound in soft tissue?
• Answer: 1,540 meters per second (m/s).
• Rationale: This is the assumed and programmed speed in all clinical
ultrasound systems. It is an average for most body tissues, though individual
tissues vary (e.g., lung is much lower, bone is higher).
Chapter 2: Transducers & Pulse-Echo Principle
5. What is the Piezoelectric Effect?
• Answer: The property of certain materials (like PZT in the transducer) to
generate an electric voltage when subjected to mechanical pressure
(Receive), and conversely, to vibrate and produce sound waves when an
electric voltage is applied (Transmit).
• Rationale: This is the core principle that allows a single transducer element
to both create and receive ultrasound waves.
6. What is the difference between continuous wave and pulsed wave
ultrasound?
• Answer:
