Light and Optical Systems - Topics 1-3 Flashcards
Light
Energy that you can see
Natural light source
A non human made source of light such as the sun or fire
Radiates
light spreads out
Radiation
The transfer of radiant energy, such as light
Radiant energy
Energy transferred as waves or rays in all directions
Artificial light source
A human made source of light. Example: light bulb
Basic Principles of Light
- Light is a form of energy
Light can be transformed into what three kinds of energy?
Thermal, electrical, chemical
Incandescent
Visible light is emitted by a hot object. Examples: candle flames, light bulbs (electricity heats a metal wire filament in the bulb, it becomes so hot that it glows)
Fluorescent
High energy invisible ultraviolet light is absorbed by the particles of an object. Example light bulbs - electricity causes mercury vapor to give off ultraviolet radiation., which is absorbed by phosphor particles to create visible light.
Light Emitting Diodes
LED - emits light when a voltage is applied to it. (electrical energy becomes light energy)
Phosphorescence
Emission of light following exposure to and removal of a source of radiation
Chemiluminescence
Emission of light resulting from chemical action and NOT involving heat. Example: glow sticks
Bioluminescent
Emission of light produced by chemical reactions inside the bodies of living things. Examples: some fish, fireflies
Cost of lighting (in 2001)
Cost = kWh X price (cents/kWh)
