Download Incandescence Light bulb has a wire filament (tungsten) that is

Incandescence
Light bulb has a wire filament (tungsten) that is heated to high temperatures by an
electric current passing through it.
Electric Discharge
Fluorescent light bulb – filled with an inert gas (eg. Argon, krypton, neon, xenon) as
well as mercury vapor. When an electric current is passed through, it causes the mercury
atoms to emit UV light. The UV light is absorbed by the fluorescent materials that coat
the tube and excites them, which makes them re-emit visible light.
Neon light has glass tubes filled with a gas like neon, argon or krypton at low pressure.
At both ends of the tube there are metal electrodes. When you apply an electric current,
the gas ionizes and electrons flow through the gas. The electrons excite the gas’ atoms
and cause them to emit light. Different gases emit different lights (neon = orange, argon
= blue, krypton = pink, xenon = purple).
Phosphorescence
Phosphor chemicals are used and there are many different kinds with various brightness,
colour and glowing time lengths. These chemicals store energy when exposed to light
and they have to be exposed for a while. When they are exposed to light, they get
energized and then radiate visible light after being energized by slowly releasing their
stored energy over time. As they release the energy, they emit small amounts of light,
making them appear to glow in the dark. Examples of common phosphors are zinc
sulphide and strontium aluminate.
Fluorescence
Fluorescent light bulb – filled with an inert gas (eg. Argon, krypton, neon, xenon) as
well as mercury vapor. When an electric current is passed through, it causes the mercury
atoms to emit UV light. The UV light is absorbed by the fluorescent materials that coat
the tube and excites them, which makes them re-emit visible light.
Chemiluminescence
Chemiluminescence makes objects glow in the dark because of a chemical energy. When
certain chemicals are mixed in a chemical reaction, they produce energy that is released
thereafter, creating a glow, as seen in fireflies and glow sticks.
Bioluminescence
A naturally occurring light source. Creatures like fireflies, anglerfishes and jellyfishes
contain special chemicals within them that cause them to glow for biological reasons (eg.
Attracting mates, courtship, attracting prey, protection, etc). In the anglerfish, the light is
used to attract prey. The light is created by masses of bacteria living in its “fishing rod”
in which the bacteria themselves are bioluminescent!
Tribioluminescence
When certain materials are broken apart, rubbed, scratched or crushed, chemical bonds
within them are broken. This separates the electric charges between, giving off sparks of
light. It is not fully understood however.
Light Emitting
Diodes (LEDs)
A semiconductor is a substance (usually a solid chemical element or compound) that can
conduct electricity under some conditions but not others – making it a good medium for
control of electric currents. Examples of elements are silicon, germanium and silicon
carbide.
When an electric current is applied, electrons located in the semiconductor material
constantly move and their movement illuminates the light bulbs.
Different from other light bulbs because it produces way less heat and is more energy
efficient. This is because the semiconductor chosen can limit the amount of energy that
flows through them.