Sources of Light, 2nd upload

Sources of Light

Incandescence

  • Definition: Light emitted from a hot body, such as a heated filament, due to its temperature.

  • Example: Incandescent light bulbs.

    • Efficiency: Very inefficient, with approximately 95% of energy converted to heat rather than light.

Bioluminescence

  • Definition: Light produced and emitted by living organisms as a result of a chemical reaction that converts chemical energy into light energy.

  • Examples:

    • Fireflies

    • Glow worms

    • Angler fish

Chemiluminescence

  • Definition: Light produced from a chemical reaction without an increase in temperature.

    • Types:

    • Non-Activated

    • Activated

      • Example: Glow sticks and “Glo” necklaces.

      • Mechanism:

        • Chemical reaction involving phenyl oxalate ester and fluorescent dye in a hydrogen peroxide solution.

        • Process:

          • When the glow stick is bent, the inner glass vial breaks, mixing the chemicals.

          • Creates a chemical reaction that produces light.

  • Example Breakdown:

    • Components:

    • Hydrogen Peroxide

    • Diphenyl Oxalate

    • Dye

    • Reaction:

    • ext{C}n ext{H}m + ext{O}2 ightarrow ext{2CO}2 + ext{Excited Dye}

  • Source: Compound Interest, 2016, under Creative Commons Attribution-NonCommercial-NoDerivatives license.

Fluorescence

  • Definition: Light produced by the absorption of radiation of one wavelength (color), followed by immediate re-radiation at a different wavelength.

  • Example: Compact fluorescent lights (CFLs).

    • Efficiency: More energy-efficient than incandescent bulbs, with approximately 80% of energy converted to heat.

Phosphorescence

  • Definition: Light energy that is stored and then re-emitted slowly over a long time.

  • Example: Glow-in-the-dark toys.

Triboluminescence

  • Definition: Light produced as a result of friction or crushing materials.

  • Examples:

    • Packing tape and duct tape

    • Quartz crystals

    • Wint-O-Green Lifesaver mints

Light-emitting Diodes (LEDs)

  • Definition: A small electric current causes semiconductor materials to emit light.

  • Energy Conversion: Converts electrical energy directly into light energy.

  • Examples:

    • LED light bulbs

    • Christmas lights

Electric Discharge

  • Definition: Light produced when an electric current passes through air or a gas.

  • Examples:

    • Lightning

    • Neon signs

    • Plasma ball