Transcript Technology and Light

Technology that Produces Light
1. Incandescence – when objects are
heated enough, they glow.
Ex. Incandescent Light Bulbs
– electricity heats up metal filament
– convert only 5% of energy into light!
2. Fluorescence – chemicals absorb UV energy
and change it into light. Different chemicals
make different colours.
Fluorescent Light Bulbs –
electricity excites mercury
and argon gas, which then
makes white powdered
coating glow. These are 20%
efficient!
Phosphors – Chemicals that
creates glow in the dark
paint.
Discharge lamps – electricity excites noble
gases, which then make different coloured
phosphors in a pixel glow. (neon lights,
plasma TV)
* LCD displays work differently - electricity
excites bands of chemicals which cause them to
turn and let light from a fluorescent bulb pass
through a coloured filter (Monitors, clocks, TV).
3. Light Emitting Diode (LED) – electricity flows
through a semiconductor which then releases
light. Very efficient but expensive (back lights).
4. Chemoluminescence – light produced by a
chemical reactions ex. glow sticks
**Some animals can do this inside their bodies
(called bioluminescence)
Video
Video2
How would your life change if we didn’t have
technology to make light?
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