Measuring waves

• The displacement of a vibrating particle is its distance and direction from the equilibrium position.
• The amplitude of a wave is its maximum displacement of a vibrating particle. For a transverse wave, this is the height of a wave crest or the depth of wave trough from its equilibrium.
• The wavelength of a wave is the distance between two of the same points on the wave.
• A cycle of a wave is the time taken for one complete oscillation of the wave. (from max displacement to the next max displacement)
• The period of a wave is the time for one complete wave to pass a fixed point.
• The frequency of a wave is the number of cycles per second. The unit of frequency is Hz.
• For waves of frequency, f, the period of a wave is 1/f.
• Wave Speed:

  • LIGHT (in air) - 3.0 × 10^8 ms−1
  • The higher the frequency of a wave, the shorter its wavelength.
  • Each wave crest travels a distance equal to one wavelength in the time taken for one cycle.

  WAVE SPEED = FREQUENCY x WAVELENGTH

  $c =$$f λ$
• The phase of a vibrating particle at a certain time is the fraction of a cycle that it has completed since the start of the cycle.
• The phase difference between two particles that are vibrating at the same frequency is the fraction of a cycle between the vibrations of the two particles, which can be measured either in degrees or radians.
• 1 cycle = 360 degrees = 2πradians
• A quarter-cycle is 90 degrees or π/2 radians.
• When two particles have a phase difference of zero they are said to be in phase with each other.
• $phase difference in radians =$$2πd/λ$