Sources of Light

Incandescence: light emitted from a hot body (a heated filament) due to its temperature Example: incandescent lightbulb (very ineffiecient, ~95% energy used as heat)

Bioluminescence: light produced and emitted by living organisms, as a result of a chemical reaction in which chemical energy is converted to light energy Examples: fireflies, glow worms, angler fish

Chemiluminescence: light produced from a chemical reaction without a rise in temperature. http://www.glowpaint.in/sticks.htm Example: glow sticks, “Glo” necklace

Fluorescence: light produced by the absorption of radiation of one wavelength (colour), followed by immediate re-radiation, usually at a different wavelength Example: CFLs (compact fluorescent lights) – more efficient than incandescent, ~80% energy used as heat

Phosphorescence: light energy is stored and then re-emitted slowly over a long time. Example: glow in the dark toys.

Triboluminsecence: light produced by friction or crushing. Example: packing/duct tape, quartz crystals, Wintogreen Lifesaver mints.

Light-emitting Diode (LEDs) small electric current causes semiconductor materials to emit light (electrical energy converted into light energy) Example: LED lightbulbs, Christmas lights

Electric Discharge: electric current passed through air or a gas. Example: lightning, neon signs, plasma ball.