Sources of Light
Students will be able to:
-Identify examples of luminous and nonluminous light
-Name examples of each type of luminous light
-Identify what each type of luminous light source needs to be produced
-Explain how each type of light source works
The Difference Between Luminous and Non-luminous:
Luminous: Objects that
produce light
Non-luminous: Objects
that reflect light
 Sun
 Moon
 Fire
 Mirrors
 Lava
Luminous or Non-Luminous?
Different Types of Luminous Light
 Incandescent Light
 Electric Discharge
 Phosphorescence
 Fluorescent Light
 Chemiluminescence
 Bioluminescence
 Triboluminescence
Incandescent Light
 Is produced by an object that is
heated to a very high temperature
 Inside an incandescent light bulb
there is a tungsten filament, which
is heated to an extremely high
temperature
 Incandescent light bulbs are
extremely inefficient
 Only 5% of the electrical energy is
converted to light
Electric Discharge
 Is a method for producing light in which an electric current
passes through the air or another gas, such as neon
 Eg. Lightning, Neon lights
Phosphorescence
 Is the ability to store the energy from a source of light and then
emit it slowly over a long period of time
 Eg. “glow-in-the-dark”
How can you recognize it? It glows and stays glowing even after you
stop shining light on it.
It needs to be charged by light before it can work. It doesn’t need
electricity or heat to work.
Fluorescent Light
 Is emitted by some substances when they




are exposed to electromagnetic radiation
In a fluorescent light bulb the mercury
vapour is energized and it emits
ultraviolet radiation
The inside of the bulb is coated with a
white powder called phosphor
The ultraviolet radiation strikes the
phosphor on the inside of the bulb,
which then glows and emits light
20% efficient
Unlike an incandescent bulb, the
fluorescent bulb uses a quarter
of the energy but contains more
toxic materials
How can you recognize it? It glows, doesn’t involve wires inside it and starts and stops
releasing its light immediately
Chemiluminescence
 Is light produced from a chemical reaction with little or no
heat produced
 Referred to as “cool light”
 Eg. Glow sticks
How can you recognize it? It involves chemicals in a chemical reaction/ It continues to
produce light until the chemicals are used up (the reactants have reacted and are now all
products). Then, it can’t produce light anymore.
Bioluminescence
 Is a type of chemiluminescence
 Is light produced from a chemical reaction by a living thing
 Eg. Blue-green stainer fungi, fireflies, deep ocean species,
algae
 TED Talk: bioluminescence
 http://www.ted.com/talks/edith_widder_glowing_life_in
_an_underwater_world.html
Triboluminesence
 Producing light from friction
 Some crystals can be made to flow simply by rubbing them
together or crushing them
Let’s Try it!!!!! - wintergreen lifesavers
How is Light Produced?
Sources of Light
Definition
Examples
Incandescence
Produced by an object that is heated to a very high
temperature
Light Bulb
Electric Discharge
Produced by electric current passing through the
air
Lightning
Neon Lights
Phosphorescence
Is the ability to store the energy from a source of
light and then emit it slowly over a long period of
time
Glow-in-the-dark
Fluorescence
Is emitted by some substances when they are
exposed to electromagnetic radiation
Light Bulb
Chemiluminescence
Is light produced from a chemical reaction with
little or not heat produced
Glow Sticks
Bioluminescence
Light produced from a chemical reaction by a
living thing
Fireflies
Triboluminescence
Producing light from friction
Crushing lifesavers