10.1 Light Energy and Its Sources
Text pages 289-293
(Visible) Light
• A form of energy that can be detected by the human eye
What is luminescence?Luminous simply means giving off light; most things in our world produce light
because they have energy that originally came from the Sun, which is the biggest,
most luminous thing we can see
Incandescence-make light by making
heat (very hot to touch!!)
Luminescent things, by contrast, make light when their atoms
become excited in a process that needs little or no heat to make it
happen.
Fluorescence: the emission of light by a substance that has absorbed light (or other electromagnetic radiation of a different
wavelength)= lower in temperature= Fluorescent materials produce light instantly= need to have electricity passed through them to keep them glowing
is a specific type of luminescence related to fluorescence. Unlike fluorescence, phosphorescence is a process in which energy absorbed by a substance is released relatively slowly (there is a delay). The object “glows” for a much longer period of time than in fluorescence
Electric discharge: electricity passing through a gas
Chemiluminescence: is the emission of light with very little heat as the result of a chemical reaction
Bioluminescence is chemiluminescence in living
organisms
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