Topic 3.3

• • Late 1800’s: Thomas Edison was the first to design light bulbs
  • He used filaments made from bamboo
• two types of light sources

  • Natural
  • Artificial
• incadecent light -

  • Thin wire inside is called the filament
  • When we turn our lights on, electrical energy flows through the filament, heating it up to extremely high temperatures
  • As the filament is heating up, it glows “white hot” creating light
  • used in easy bake ovens
• incandescent light -

  • Produces about 95% heat and 5% light
  • Electrical energy-thermal energy-visible light energy
• fluorescent light -

  • A glass tube filled with a small amount of gas (ex. Mercury vapor)
  • The inside of the bulb is coated with a white powder called phosphor
  • As electricity passes through the bulb, the gas in the bulb will emit ultraviolet radiation
  • This strikes the phosphor, which glows, and emits visible white light
  • This emission is called fluorescing
• Phosphorescent light -

  • Process in which a substance emits light AFTER it has absorbed ultraviolet radiation
  • They can store energy from the radiation, then emit light after the source of radiation has stopped
  • glow in the dark irems
  • Can be re-energized by being held under a lamp for a few minutes
• chemiluminescent light -

  • light emitting from a chemical reaction
  • glow sticks
• LED lights- light emitting diode

  • Considered very efficient and have a much longer lifespan than incandescent and fluorescent lights
  • Light is produced by movement of electrons – no heat is required