Em Waves

• Electromagnetic spectrum


  The energy field created by electricity and magnetism that can oscillate and support waves that move
• Electromagnetic waves


  • Have both an electric part and a magnetic part that exchange energy back and forth
  • Have a wavelength (λ) and amplitude (A)
• Higher frequency of light


  Higher energy of the wave
• Color


  Directly related to energy, frequency, and wavelength
• Calculating wavelength


  Given frequency, solve for wavelength using speed of light formula
• Waves of the electromagnetic spectrum

  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • Ultraviolet
  • X-rays
  • Gamma rays
• Interference pattern


  Alternating bright and dark bands formed when light passes through parallel slits
• Diffraction grating


  Precise array of tiny engraved lines that allow light through and produce a spectrum
• Spectrometer


  Device that measures the wavelength of light using a diffraction grating
• Polarization


  A wave property of light that indicates it is a transverse wave
• Polarizer


  Material that selectively absorbs light depending on polarization and re-emits a fraction of incident light polarized at an angle to the transmission axis
• Applications of polarizers


  • Polarizing sunglasses
  • LCD screens
• Special relativity

  Theory that describes what happens to matter, energy, time, and space at speeds close to the speed of light
• Implications of special relativity


  • Time moves more slowly for an object in motion (time dilation)
  • Mass increases as objects move faster
  • Definition of "simultaneous" changes
  • Space itself gets smaller for an observer moving near the speed of light
• The theory of special relativity comes from thinking about light