luminous source produces its own light eg. the sun, a light bulb, a camp fire, a firefly ...
TRANSCRIPT
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