Section 3.3 Visible Light

Light is a form of energy Simply stated, light is the form of energy you can see. This energy can be produced naturally by the sun or fire, or artificially by light-producing technologies, like batteries. Radiation is the wave like transfer of light from its source in all directions. Light is often called radiant energy. Light from the sun is formed by nuclear fusion.

1st Basic Principal of Light 'Light is a form of energy' When light reaches a surface, it can be absorbed and transformed into other types of energy.

Electrical Energy Solar energy is converted to power the home

Thermal Energy Cameras turn light into thermal images

Chemical Energy Trees convert light into food/energy

Intensity The amount of energy a surface receives depends on the intensity of the light. The more intense the light, the more light can be absorbed.

Sources of Light

Sources- (Where does light come from?) Brainstorm common examples (light bulb…) then categorize Heat/Thermal ex. Sun, fire Incandescent Fluorescent Phosphorescent Bioluminescent Chemiluminescent

Incandescent The filament of tungsten in a light bulb gets so hot, that it emits light energy

Fluorescent Electricity excites mercury gas in a tube, which emits UV light (ultraviolet) This light is absorbed by a phosphor coating, causing it to “fluoresce” into visible energy

Fluorescent minerals Some minerals will “fluoresce” under a black light Ex: “fluorine”

Black light (UV) Black light: lamp emitting electromagnetic radiation that is almost exclusively in the soft near ultraviolet range, and very little visible light.

Neon Bowling/Laser Tag”

Incandescent vs. Fluorescent $ cheaper for bulbs $$$ less efficient (loses energy as heat) Have to buy often, fills up landfill $$$ expensive bulbs $ more efficient (uses less energy) Mercury is not safe for the environment

Phosphorescent Glow in the Dark Emission of light following exposure to and removal of a source of radiation

Bioluminescent Bio: living Luminescent: luminous =emits light ….light produced by living organisms Ex. Fireflies, jelly fish, angler fish (finding Nemo)

Chemiluminescent Chem-chemical Luminescent: emits light ….chemical source of light Ex. Glow sticks