Luminous Source produces its own

light eg. the sun, a light

bulb, a camp fire, a firefly

Non-Luminous Source: does not produce its

own light. eg. the moon, a person,

a pencil

IncandescenceElectric DischargePhosphorescenceFluorescenceChemiluminescenceBioluminescence

the production of light as a result of high temperature

produced by a light bulb, a candle, molten metal.

electricity passes through a thin wire filament which gets so hot that it gives off visible light and infrared light.

bulbs contain non-reactive gases so that the filament can’t react with oxygen.

very inefficient source of light because only 5%-10% of the electricity is converted to visible light.

up to 95% of the electric energy is wasted on the production of heat (infrared radiation).

Video: How a lightbulb works

the production of light by passing an electric current through a gas.

different gases produce different colors of light (e.g., Neon gas produces red light).

lightning is a form of electric discharge through the air of Earth’s atmosphere.

Video: Neon Lights

fluorescence occurs when an object absorbs ultraviolet light and immediately releases the energy as visible light.

tube is filled with mercury vapourelectricity causes vapour to emit

ultraviolet light.ultraviolet light strikes fluorescent

material in inner surface of glass and causes visible light

Video: How Fluorescent Lights work

since much less energy is lost as heat, fluorescent bulbs are about 5 times more efficient than incandescent bulbs

Because they contain small amounts of mercury vapour, care must be taken when disposing of compact fluorescent bulbs

some materials absorb ultraviolet energy and hold onto it while slowly releasing visible light over a period of time

glow-in-the-dark objects

production of light as a result of a chemical reaction with little or no heat production

used in situations when it is unsafe to use electricity ie. underwater divers

Video: Glowsticks

production of light in living organisms as a result of a chemical reaction with little or no heat production

Video: Glow Worms Video: Fish

Read pg. 403-410Do #3 – 5, 8 on pg. 410