Waves term 1

• Transverse pulses
• Pulse


  • A single disturbance in a medium
• Transverse pulse


  • Particles of the medium move at right angles to the direction of motion of the pulse

  
• Pulse speed


  v = D / Δt
• Interference


  The overlapping of two pulses when they coincide
• Superposition


  The algebraic sum of the amplitudes of two pulses that occupy the same space at the same time
• Constructive interference


  Crest of one pulse overlaps with crest of another to produce pulse of increased amplitude
• Destructive interference


  Crest of one pulse overlaps with trough of another, resulting in pulse of reduced amplitude
• Transverse wave


  • Particles of medium vibrate at right angles to direction of motion of wave

  
• Amplitude


  Maximum displacement of particles from rest position
• Wavelength


  Distance between two consecutive points in phase
• Crest


  Highest point (peak) on a wave
• Trough


  Lowest point on a wave
• In phase


  Points separated by whole number multiple of completed wavelengths, following identical motion
• Totally out of phase


  Points following exactly opposite path
• Partially out of phase


  Points not separated by whole number multiple of completed wavelengths, following different paths
• Wave speed calculation


  1. v = D / Δt

  2. v = f λ

  
• Frequency


  Number of waves per second, unit: Hz
• Period


  Time taken for one complete wave, unit: s
• Frequency and period


  f = 1 / T
• Longitudinal wave


  • Particles of medium vibrate parallel to direction of motion of wave

  
• Compression


  Region of high pressure in longitudinal wave
• Rarefaction


  Region of low pressure in longitudinal wave
• Frequency calculation


  f = number of waves / total time
• Period calculation


  T = total time / number of waves
• Frequency and period


  T = 1 / f
• Sound is created by vibrations in a medium in the direction of propagation (longitudinal wave)
• Sound waves are 3D longitudinal waves that travel through solids, liquids and gases but not through a vacuum
• Frequency


  What the human ear perceives as pitch