Characteristics of Waves

Key Definitions in Wave Characteristics

  • Wave Speed: The speed at which a wave travels through a medium.
  • Wave Velocity: A vector quantity that depicts the direction and speed of a wave.
  • Wavelength (λ): The distance between two consecutive points on a wave that are in phase; measured from crest to crest or trough to trough.
  • Frequency (f): The number of waves passing a point in one second, measured in Hertz (Hz).
  • Period (T): The time taken for one complete wave (or cycle) to pass a given point, related to frequency as ( T = \frac{1}{f} ).

Wave Types

Transverse Waves

  • Definition: Waves where particle movement is perpendicular to the direction of the wave's velocity.
  • Key Features:
    • Crests & Troughs: High points (crests) and low points (troughs) of the wave.
    • Amplitude (A): Measure of energy contained in the wave, defined as the distance from the baseline to the crest or trough.
  • Wave Phase:
    • In Phase: Points on consecutive waves that are the same (360° apart).
    • Out of Phase: Points that are not the same; for instance, points that are 180° apart are halfway between crests and troughs.

Longitudinal Waves

  • Definition: Waves in which particle vibration is parallel to the direction of wave velocity.
  • Key Features:
    • Compressions and Rarefactions: Areas of high density (compressions) and low density (rarefactions).
    • Amplitude in longitudinal waves: Related to the density difference between compressions and rarefactions.

Practical Examples

  • Determining Wavelength in a Transverse Wave:
    • Find the same point on consecutive cycles.
    • Example: Points A and E, B and F, or C and G.
  • Identifying Points in Phase:
    • Example: A point (P) at the baseline crossing corresponds to another point (C) at the same position in another wave.
  • Amplitude Calculation:
    • Points A and D can denote the amplitude if their distance measures from the baseline to the crest or trough.

Sample Problems Breakdown

  1. Amplitudes: If multiple sets of points are given, measure between the baseline and crests (or troughs).
    • Example: Between A (baseline) and D (crest)
  2. Wave Direction and Particle Motion: Particles vibrate in the wave's direction.
    • Example: If the wave moves to the right, particles like position C will move right and left.
  3. Frequency Impact on Amplitude: Striking a tuning fork harder increases amplitude.
    • Example: More energy corresponds to greater amplitude.
  4. Measuring Wavelengths: Identify same positions between consecutive waves to measure accurately.
    • Example: Points A and C as consecutive same points.

Additional Resources

  • For further study, consider visiting A+ Physics.com or using the review books:
    • "Regents Physics Essentials" for New York Regents classes.
    • "Honors Physics Essentials" for algebra-based physics classes throughout the country.