Wave Motion and Medical Applications

Wave Motion and Waves on a String

• Wave motion is categorized into different types, including transverse and longitudinal waves.
• Sine wave characterization is vital for applications in medical fields, such as interpreting ECG signals.
• Standing waves are formed when two waves of identical frequency and amplitude interfere in opposite directions.

Applications in Medicine

• Ultrasound Imaging: Utilizes mechanical waves to visualize internal organs non-invasively.
• Therapeutic Ultrasound: Heats tissues for healing using sound waves.
• Electrocardiography (ECG): Sine waves represent heart activity, helping diagnose cardiac issues.
• MRI Imaging: Utilizes standing waves for detailed imaging, focusing on hydrogen atom interactions.
• Lithotripsy: Focused ultrasound waves disrupt kidney stones via acoustic resonance.

Wave Types

• Transverse Waves: Particle oscillation is perpendicular to wave propagation; examples include electromagnetic waves and waves on strings.
• Longitudinal Waves: Particle oscillation is parallel to the direction of wave movement; sound waves exemplify this with compressions and rarefactions.
• Mechanical Waves: Require a medium (solid, liquid, gas) to travel. Examples include sound and water waves.
• Non-Mechanical Waves: Can propagate through vacuum via oscillating electric and magnetic fields. Examples are light and X-rays.

Wave Speed

• The relationship between wave speed (v), frequency (f), and wavelength (λ) is given by v = f × λ.
• Wave speed is calculated using wavelength and period; as period is the inverse of frequency, v can also be expressed with these values.

Wave Interference

• Occurs when multiple waves overlap, causing a combined wave pattern.
• Constructive Interference: When crests overlap, resulting in increased amplitude.
• Destructive Interference: Crest overlaps with a trough, reducing amplitude or canceling out the wave.
• This phenomenon creates patterns, exemplified by ripples from stones thrown into water.

Standing Waves Characteristics

• Created by interference of two waves traveling in opposite directions.
• Features distinct nodes (points of no vibration) and antinodes (points of maximum vibration).
• Energy is not transferred in stationary waves; they remain in a fixed position.

Laws of Transverse Vibrations of a String

• Law of Length: Fundamental frequency is inversely proportional to the string length (f ∝ 1/L, other factors constant).
• Law of Tension: Frequency is proportional to the square root of tension (f ∝ √T, other factors constant).
• Law of Mass: Frequency is inversely proportional to the square root of mass per unit length (f ∝ 1/√μ, other factors constant).
• Combined, these laws yield the equation: f = (1/2L)√(T/μ).

Sonometer

• A sonometer is used to study the frequency of vibrating strings in relation to their properties.
• Structure includes a resonating wooden box, stretched strings, a pulley system for tension adjustment, movable bridges for altering vibrating length, and tuning forks for resonance demonstration.
• The device illustrates principles of sound waves and resonance through experimentation.

Practical Examples

• Calculated frequency from a heart rate of 75 beats/min equates to 1.25 Hz; period is 0.8 s.
• For a water wave, oscillation at 3 Hz with a 2 m wavelength results in wave speed of 6 m/s.

Conclusion

• Understanding wave motion is crucial in both theoretical and practical applications, particularly in medical technology and fundamental physics.

This quiz explores wave motion, including types of waves like transverse and longitudinal, and their applications in medicine. It covers essential concepts such as ultrasound imaging, electrocardiography, and MRI, highlighting how wave characterization is crucial for various medical technologies.