waves

• Waves


  Oscillations of particles or oscillations of a field
• Waves


  • Can transfer energy
  • Can store energy
• Progressive wave


  Waves that transfer energy
• Types of progressive waves


  • Longitudinal
  • Transverse
• Longitudinal wave


  Particles oscillate in the same direction as the energy transfer
• Transverse wave


  Particles oscillate at 90 degrees to the direction of energy transfer
• Displacement


  Positive or negative movement of a particle
• Amplitude

  Height of the wave
• Waves


  Oscillations of particles or oscillations of a field
• Waves


  • Can transfer energy
  • Can store energy
• Progressive wave


  Waves that transfer energy
• Types of progressive waves


  • Longitudinal
  • Transverse
• Longitudinal wave


  Particles oscillate in the same direction as the energy transfer
• Transverse wave


  Particles oscillate at 90 degrees to the direction of energy transfer
• Displacement


  Positive or negative movement of a particle
• Amplitude


  Height of the wave
• Wavelength


  Distance from one wave to the equivalent point on the next wave
• Time period


  Time from one part of the wave to the equivalent part of the next wave
• Frequency


  Number of wave cycles per second
• Phase


  Part of the wave cycle that a point is in
• Phase can be represented in degrees or radians
• Examples of longitudinal waves


  • Sound waves
  • Ultrasound
• Examples of transverse waves


  • Electromagnetic spectrum
  • Waves on a string
  • Water ripples
• In a vacuum, electromagnetic waves travel at the speed of light (3.00 x 10^8 m/s)
• Speed of a wave


  C = f * λ (where C is speed, f is frequency, and λ is wavelength)
• Polarisation


  Transverse waves can be polarised, longitudinal waves cannot
• Polarisation is useful for things like sunglasses and radio antennas
• Stationary wave


  Formed when a progressive wave reflects and interferes with itself
• Node


  Position of no displacement in a stationary wave
• Anti-node


  Position of maximum displacement in a stationary wave
• Constructive interference


  Occurs when waves combine to increase amplitude
• Destructive interference


  Occurs when waves combine to decrease amplitude
• Stationary waves can be demonstrated with microwaves and sound waves
• Diffraction


  The spreading out of waves as they pass through an opening or around an obstacle
• Laser light is monochromatic and coherent, allowing interference patterns to be observed
• Laser light


  Light amplification by the stimulated emission of radiation
• Laser light


  • Monochromatic - all the same wavelength
  • Coherent
• Wavelength of laser light

  Similar to the gap size for maximum diffraction
• Shining laser light through a double slit

  1. Diffraction pattern with maxima and minima

  2. Fringes of light
• Width of fringes (W)


  Equals lambda D divided by s (distance between slits)