Section Summary

Sections
Section Summary

Section Summary

  • A wave is a disturbance that moves from the point of creation and carries energy but not mass.
  • Mechanical waves must travel through a medium.
  • Sound waves, water waves, and earthquake waves are all examples of mechanical waves.
  • Light is not a mechanical wave since it can travel through a vacuum.
  • A periodic wave is a wave that repeats for several cycles, whereas a pulse wave has only one crest or a few crests and is associated with a sudden disturbance.
  • Periodic waves are associated with simple harmonic motion.
  • A transverse wave has a disturbance perpendicular to its direction of propagation, whereas a longitudinal wave has a disturbance parallel to its direction of propagation.
  • A wave is a disturbance that moves from the point of creation at a wave velocity vw.
  • A wave has a wavelength λ λ, which is the distance between adjacent identical parts of the wave.
  • The wave velocity and the wavelength are related to the wave’s frequency and period by v w = λ T v w = λ T or v w =fλ . v w =fλ .
  • The time for one complete wave cycle is the period T.
  • The number of waves per unit time is the frequency ƒ.
  • The wave frequency and the period are inversely related to one another.
  • Superposition is the combination of two waves at the same location.
  • Constructive interference occurs when two identical waves are superimposed exactly in phase.
  • Destructive interference occurs when two identical waves are superimposed exactly out of phase.
  • A standing wave is a wave produced by the superposition of two waves. It varies in amplitude but does not propagate.
  • The nodes are the points where there is no motion in standing waves.
  • An antinode is the location of maximum amplitude of a standing wave.
  • Reflection causes a wave to change direction.
  • Inversion occurs when a wave reflects from a fixed end.
  • Refraction causes a wave’s path to bend and occurs when a wave passes from one medium into another medium with a different density.