Waves

• Outward oscillations from a source are progressive (travelling) waves
• Transverse wave


  • Oscillations of the medium are perpendicular to the direction of energy transfer
  • Direction of energy transfer
• Longitudinal wave


  • Oscillations of the medium are in the direction of energy transfer
  • Direction of energy transfer
• EM waves and Seismic S-waves are examples of waves
• Refraction


  • Waves changing direction crossing an interface between media with different wave speeds (e.g. different optical density)
  • Frequency can't change
• Reflection


  • Angle of incidence = Angle of reflection
  • Frequency, wavelength, wave speed unchanged
• Diffraction


  • The spreading of a wave from around an obstacle or through a gap
• Electromagnetic waves


  • Consist of electric and magnetic waves travelling together oscillating perpendicular to one another and the propagation direction
  • In phase with one another
• Plane polarised wave


  Transverse waves where the vibrations stay in one plane only
• Unpolarised wave


  Transverse waves where the vibrations change from one plane to another
• Longitudinal waves cannot be polarised
• Applications of polarisers


  • Glare from reflected light
  • Aerials