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ch 15 physics
definitions
| Term | Definition |
|---|---|
| continuous spectrum | |
| spectrograph | the photograph, product or print out produces by a spectroscope |
| light year | used to measure the distance of stars. equals the distance light travels in one year |
| intensity | the light sources power, rate at which it radiates energy ...aka brightness |
| candela | SI unit used to measure brightness. based on the emission of light from solidifying platinum |
| inverse square law | illumination is inversely proportional to the square of the distance from the light source. pg 357 |
| incandescence | light produced by materials heated until they glow . results when atoms and their electrons vibrate rapidly with thermal energy |
| fluorescence | occurs when a substance radiates visible light as it absorbs a higher energy form of EM energy |
| phosphorescence | similar to fluorescence but the object continues to emit visible light after the energy source is removed |
| coherent light | produces monochromatic light. consists of photons that have the same wavelengths (same color). extremely bright (lasers ,LEDs) |
| cold light | produced from chemical reactions at temps. far below those required for incandescence . bioluminescence and chemiluminescence are types of it (fire flies and glow sticks) |
| primary hue | human brain can distinguish 3 colors of light (red ,blue,green) that can be mixed to produce most other hues aka additive primary colors |
| additive primary color | aka primary hue :red blue green |
| subtractive primary color | cyan, magenta, yellow. mixing produces more brilliant colors . mixture of to addictive colors |
| complementary color | subtractive primary colors are _______ to additive primary colors. |
| saturation | the intensity /brightness of a color |
| value | how light or dark the color appears |
| beam | a straight line projection of light which is made of many photons moving in the same direction |
| ray | line with an arrow head showing direction |
| diffuse reflection | most common type. rough or uneven surfaces reflect light rays in all directions |
| spectacular reflection | produced by smooth polished surface such as metal or glass . reflect all the light rays from a source in generally the same direction . forms an image of the light source |
| incident ray | the light ray approaching an object |
| reflected ray | the outgoing ray that bounces off the object |
| law of reflection | the angle of incidence equals the angle of reflection |
| plane mirror | a flat mirror. image appears upright image an equal distance away on the opposite side of mirror |
| virtual image | seen in a position but no real object exists behind the mirror. image exists as construction made by brain from reflected light rays |
| real image | formed when rays of light from a source are made to converge or come together by a focusing optical device |
| concave mirror | slightly dished on the reflected side. |
| principal optical axis | an imaginary line normal (perpendicular) to the mirrors surface at the center |
| principal focus | light rays reflected and converge on the point in front of the mirror |
| focal point | aka principal focus. ... light ray reflected focus on this point |
| focal length | principal focus lies on the optical axis at a distance from the mirrors center |
| convex mirror | surface bulges outward. cannot produce real image because all light rays reflected off the convex surface diverge even more than from a plane mirror |
| optical density | a measure of the materials ability to transmit or absorb light |
| index of refraction | the ratio of the speed of light in a vacuum to the speed of light in the material. h=c/v. always greater than one |
| total internal reflection | the angle of incidence is increased to the point here the light ray bounces back into the original material |
| critical angle of incidence | the angle of incidence at which this phenomenon begins |
| fiber optics | growing field of technology. thin rods of glass to transmit light ...has helped with surgeries and such |
| light dispersion | when a light ray passes through the boundary between two materials, its angle of refraction depends on its frequency as well as its angle of incidence. higher frequency will bend more |
| lens | a disk of optically clear material that refracts light to produce a real or virtual image |
| converging lens | collects incoming rays of light and focuses them on a pint |
| diverging lens | collects incoming rays of light and spreads them apart |
| meniscus lens | corrective lenses compensate by focusing light rays on exactly the retina .both sides of the lenses are curved in the same direction |
Created by:
NinaTest
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