Wave Properties of Light

• Sir John Joseph Thompson

  Discovered the electron, the first subatomic particle
• George Thompson


  Discovered the wave properties of an electron by diffraction
• Electrons are both a particle and a wave at the same time
• Electron


  • Has a definite mass and definite charge
  • Often portrayed as a solid particle orbiting a nucleus of an atom
• Double-slit experiment by Thomas Young

  1. Electrons are fired at a barrier with two narrow slits either simultaneously or one at a time

  2. Interference pattern formed on the screen
• Interference patterns are series of alternating bright and dark bands that are more of a characteristic of waves, rather than of particles
• Dispersion


  Separation of white light into a spectrum of colors by the process of refraction
• Dispersion


  • When white light passes from air into a glass prism, it splits into rainbow colors, ROYGBIV
  • Violet bends the most, and red bends the least
• Scattering


  Process where light rays deviate from its path due to non-uniformities in the medium through which they pass
• Scattering


  • Non-uniformities include dust particles, gas molecules, droplets, etc.
• Interference


  Phenomenon that occurs when two light waves meet while traveling along with the same medium
• Interference


  • Superposition principle is the basic principle used
  • Incoming light waves can either superimpose constructively or destructively
• Constructive Interference


  Occurs when the two interfering waves have a displacement in the same direction
• Destructive Interference


  Occurs when two interfering waves are with opposite displacements
• Diffraction


  Process in which a light ray travels through an obstacle or around a barrier and it spreads out as a result
• Diffraction


  • Sending light rays through a slit will spread it out that makes a wider stream of light
  • The smaller the slit, the greater the diffraction effect
  • Diffraction also produces interference patterns