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Difficulty: MediumPhysics Fundamentals and Everyday Applications

Consider everyday applications and principles of wave physics and acoustics. Which of the following statements are correct?

  1. Ultrasonic waves are widely utilized in medical sonography because their short wavelength allows high spatial resolution for imaging soft tissues.Answer
  2. B
    The increase in observed pitch when an ambulance siren approaches a stationary listener is caused by an increase in the sound frequency actually produced by the siren.
  3. SONAR (Sound Navigation and Ranging) technology relies on the reflection of ultrasonic acoustic pulses to determine the distance and depth of submerged objects.Answer
  4. D
    Acoustic reverberation in large halls occurs primarily due to the total absorption of sound energy by soft wall materials.

Answer

The correct statements are that ultrasonic waves are utilized in medical sonography due to their short wavelength yielding high spatial resolution, and SONAR technology relies on the reflection of ultrasonic acoustic pulses to measure underwater distances.
Ultrasonic medical imaging relies on short wavelengths for high spatial resolution, and SONAR relies on acoustic reflection to calculate depth. Both statements accurately describe sound wave phenomena.

Step-by-Step Solution

1
Analyze the sound resolution characteristics of ultrasonic waves
Since wave speed v=fλv = f \lambda, higher frequency ff corresponds to smaller wavelength λ\lambda. Smaller wavelengths experience less diffraction around small objects, providing high-resolution images in medical ultrasound.
Resolving power increases as the wavelength of the probing wave decreases.
2
Evaluate the mechanism behind the Doppler Effect
Relative motion between source and observer changes the arrival rate of wave fronts, causing an apparent frequency shift f′=f(vv−vs)f' = f \left(\frac{v}{v - v_s}\right). The intrinsic source frequency ff remains constant.
Distinguishing between emitted source frequency and observed relative frequency is critical for Doppler analysis.
3
Examine SONAR operating principles and reverberation physics
SONAR uses echo timing of reflected ultrasound pulses (d=v⋅t2d = \frac{v \cdot t}{2}). Reverberation stems from multiple specular and diffuse reflections off boundaries, whereas porous absorbent materials damp reverberation.
Acoustic reflection enables distance measurement in SONAR, while reflection persistence causes reverberation.

Key Concept

Ultrasonic wave applications, Doppler effect mechanism, and acoustic reflection
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Topics

Physics Fundamentals and Everyday Applications

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