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Light Energy
Term | Definition |
---|---|
Luminous | Objects that emit light |
Non-Luminous | Objects that do not emit light (But they can reflect light) |
Give an example of luminous and non-luminous objects | Luminous - Sun; Non-luminous - Moon |
Incadesence | Process of emitting light at high temperature (ie: candle, torch, light bulb) |
Phosphoresence | Process of emitting light after energy has been stored for a short period of time |
Example of phosphorus object | Glow-in-the-dark stickers |
Electric Discharge | Process of emitting light by running electricity through a gas |
Example of electric discharge | Neon lights, lightning |
Fluoresence | Emitting light while receiving energy from another source - combines electric discharge with phosphoresence |
Chemiluminescence | Process of changing chemical energy into light energy - produces little or no heat |
Example of chemiluminescence | Glow sticks |
Bioluminesence | Light emitted from a living organism - use chemical activity to emit light |
Example of bioluminescence | Angler fish, fireflys, glow worms |
How does a fluorescent bulb work? | Electricity runs through mercury vapour. The vapour emits ultra violet light. The ultra violet light will "light up" a phosphorous film on the glass and the bulp glows. |
How does an incandescent bulb work? | Electricity runs through the filament causing it to heat up and glow. |
What is the energy transformation for incandescent objects? | Electrical energy --> Thermal energy (heat) --> Light |
Umbra | Dark part of a shadow |
Penumbra | Light part of a shadow |
Shadow | Area where light has been blocked by a solid object |
Transparency | Measure of how much light can pass through a material |
Transparent | Materials allow all light to pass through |
Translucent | Materials allow some light to pass through |
Opaque | Materials allow no light to pass through |