types of light sources Flashcards
What are the different types of light sources?
Natural and artificial.
What do all sources of light do?
Must absorb some form of energy that raises atoms to an excited state.
What do excited atoms do?
release vast amounts of energy called light
How does the sun provide light?
nuclear/fusion reactions.
What do fusion reactions do?
Release vast amounts of energy.
What is incandescent light?
Light emitted from a material at a high temperature.
How do incandescent light bulbs work?
Have tiny tungsten wires that get very hot when an electric current runs through them.
How do streetlight bulbs work?
Electric discharge. Emit light from a gas/vapour instead of a heated wire.
What is fluorescent light?
Light emitted during the exposure of the source to ultraviolet light.
How do fluorescent light bulbs work?
Phosphor emits visible light when bombarded by ultraviolet light produced by excited mercury atoms.
Why are fluorescent light bulbs better?
Uses less energy, and lasts longer.
What is luminescent light?
Light generated without heating the object. Energy used to excite atoms comes from a variety of sources.
What is phosphorescence?
Type of luminescence. Many glow-in-the-dark objects contain phosphorescent materials. Excited atoms may retain energy for several mins/up to a few hours.
What is chemiluminescence?
Light generated by the energy released in a chemical reaction without a rise in temp.
What is bioluminescence (with examples)?
Light produced by a biochemical reaction in a living organism (krill, jellyfish).
