1. Sources of Light

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

3. 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

4. Chemiluminescence: light produced from a chemical reaction without a rise in temperature.
Example: glow sticks, “Glo” necklace

6. 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

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

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

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

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