Light waves

• Sir John Joseph Thompson


  Scientist who discovered the electron, the first subatomic particle
• George Thompson

  Son of Sir Joseph John Thomson, won Nobel prize for discovery of wave properties of electron
• Sir Joseph John Thomson won a Nobel prize with his discovery of the electron
• George Thompson won a Nobel prize for his discovery of the wave properties of an electron by diffraction
• Electron

  • Behaves like both a particle and a wave
• There is evidence that electrons behave like particles
• Electron

  A subatomic particle with definite mass and charge, often portrayed as a solid particle orbiting a nucleus
• Double-slit experiment


  1. Electrons fired at a barrier with two narrow slits

  2. Interference pattern formed on detector screen
• Interference pattern

  are series of alternating bright and dark bands that has a characteristic of waves, rather than of particles
• Dispersion

  • Separation of white light into a spectrum of colors by refraction
  • Violet bends the most, red bends the least
• Scattering

  • Light rays deviate from path due to non-uniformities in medium like dust particles, gas molecules, droplets
• Interference


  • Occurs when two light waves meet and superimpose constructively or destructively
• Constructive interference

  Occurs when interfering waves have displacements in same direction, intensity increases
• Destructive interference


  Occurs when interfering waves have opposite displacements, intensity decreases
• Diffraction


  • Light ray travels through obstacle or around barrier and spreads out
  • Smaller the slit, greater the diffraction effect
• Superposition


  basic principle used in the interference of light