Types of Light Flashcards
1
Q
What is incandescence light?
A
- The production of light as a result of high temperatures
- Ex. Incandescence light bulb, burning canfdle
2
Q
What is an incandescent light bulb?
A
- A light bulb has a tungsten wire that gets very hot and glows brightly when electric current runs through it
- Electric energy ‘excites’ the atoms that give off heat and light
- Very inefficient source of light because more heat is produced than light
3
Q
What is electric discharge?
A
- The process of producing light by passing an electric current through a gas
- Electricity causes the gas to glow
- ‘neon’ lighting’ - but not usually neon is used
- Different gases give off different colours.
4
Q
What is phosphorescence light?
A
- The process of producing light by the absorption of UV light resulting in the emission of visible light over an extended period of time
- Ex. glow in the dark objects
- Coated with special materials called phosphors
5
Q
What is fluorescence light?
A
- The immediate emission of visible light as a result of the absorption of UV light
- Fluorescent dyes are often added to detergents to make clothes ‘brighter’
- Highlighters contain fluorescent ink
6
Q
What are some uses of fluorescence?
A
- Many body fluids contain fluorescent molecules
- UV light plus luminol can be used to see them
- Fluorescent material used in documents, money & tickets
7
Q
What is a compact fluorescent light bulb?
A
electric discharge + fluorescence
- Bulb is filled with mercury vapour
- Inner tube is coated with fluorescent material
- When light is turned on, electric current causes the mercury atoms to emit UV light
- UV light strikes the fluorescent coating of the tube, resulting in the emission of visible light
8
Q
What is chemiluminescence?
A
- The direct production of light as the result of a chemical reaction with little or no heat produced
- Example: glow sticks
9
Q
What is bioluminescence?
A
- The production of light in living organisms as the result of a chemical reaction
- Chemical reactions in living cells
- Common in marine organisms
10
Q
What is triboluminescence light?
A
- The production of light from friction as a result of scratching, crushing or rubbing certain crystals
- Wintogreen lifesavers
- Duct tape
- Does not appear to have any practical application … for now.
11
Q
What are LED lights?
A
Light-emitting diode
- light produced as a result of an electric current flowing through semiconductors (only allows current in 1 direction) E.g. of a semiconductor = silicon
12
Q
Compare LED and incandescent lights
A
Compared to incandescent lights LED lights
- no filament required
- Not as much heat produced
- More energy efficient
