10.2 Producing Visible Light
Sources of Light
Natural light
-produced by sun
through or stars
Artificial light
-produced human
technology
Incandescent light sources
 Light produced by an object that was
heated
Ex. Incandescent light bulb
-electricity heats a metal filament
called
tungsten which produces light
Luminescent light
 Light is releases by an object that has NOT
been heated
 There are several types of luminescent light
-Fluorescent
-triboluminescence
-phosphorescent
-electric discharge
-chemiluminescent
-bioluminescence
Fluorescent Light
-light is emitted by an object
when it is exposed to
ultraviolet radiation
Ex. Fluorescent light bulbs
are coated with a white
powder called a phosphor
and contain a small amount
of gas. The phosphor will
glow after being exposed to
energized particles
(electricity energized the
gas)
Phosphorescent light
 A substance that can store energy
from radiation will emit light slowly
over a long period of time
 Glow in the dark after being
energized by light
Ex. Glow in the dark paint
Chemiluminescent
 Light is produced
from a chemical
reaction without a
rise in temperature
 Light produced is
called “cool light”
Ex. Glow in the dark
sticks
Bioluminescence
 Special kind of chemiluminescence
 A plant or animal produces light
Triboluminescence
 Light is produced by friction
 Some crystals glow by rubbing them
together
Ex. quartz
Electric Discharge
 Electric current is passed through the
air or another gas
Ex. Neon signs
carbon arc light
Light Emitting Diode (LED)
 Electrical energy is transformed directly into
light energy (electroluminescence)
 Consume less energy than
fluorescent/incandescent devices and last
longer
 LED’s are made out of semiconductors (can
change how well it conducts electricity) – they
emit light when electricity is passed through
it.
Homework
 P. 395 #1-5
 P. 398 #1-5