Unit 8: Electromagnetic Waves

• Electromagnetic wave


  A wave generated by a disturbance in electric and magnetic fields
• Electromagnetic waves


  • Can move through areas without a medium (space)
  • Transport energy
  • Speed is constant no matter the medium or lack there of
  • Disturbance needs to be periodic
• Electromagnetic spectrum


  The range of wavelengths of electromagnetic waves
• Electromagnetic spectrum[examples]

  • Radio waves (longest wavelength)
  • Gamma rays (shortest wavelength)
• Smaller wavelength

  More energy, higher frequency
• Properties of EM waves

  • All EM waves move at the speed of light
  • Can all be modeled as transverse waves
• Visible Light


  EM waves we can see
• Visible Light [range]


  380 nm to 740 nm
• Visible light


  White light contains all wavelengths of light and can be separated by a prism by refracting the light
• Ray


  A model for waves that uses an arrow to represent direction
• Rays


  • Always drawn perpendicular to the wave fronts
  • Look like electric fields and magnetic fields
• Diffraction


  The bending of a wave around the edges of an opening or an obstacle
• Reflection


  A phenomenon that occurs when a wave or object bounces off an interface or another object
• Models for reflection


  • Ray model
  • Wave model
  • Particle model
• Lens


  A piece of glass or other transparent substance with curved sides that is used for concentrating or dispersing light rays
• Converging lens (convex lens)


  Shaped so light converges to a singular point