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30 Cards in this Set
- Front
- Back
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electromagnetic radiation
long wave length = |
short energy (Infrared, Radio Wave)
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electromagnetic radiation
short wave length = |
high energy (Gamma rays, X-rays, UV light)
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wave-photon duality
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light travels in wave-like fashion with "single packets" of energy called photons
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visible spectrum
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different colors of light have different wavelengths
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Violet
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380nm
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Blue
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480nm
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Green
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550nm
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Yellow
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630nm
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Orange
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680nm
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Red
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730nm
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color of an object
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determined by which wavelengths are REFLECTED back to the retina (not absorbed by the object)
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white
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all wavelengths reflected by object
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black
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all wavelengths absorbed by object
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light refraction
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light will bend when it passes from one medium (air) into another (lens) e.g. pencil in glass of water
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convex lens
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(thicker at center, tapered at edge) causes light to bend so that it comes together at a focal point
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real image
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image at focal point of convex lens --> inverted & reversed
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focusing light on the retina
cornea |
constant (unchanging) refraction
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focusing light on the retina
lens |
can change refraction and focal length; ciliary muscles change convexity of the lens
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Focusing for Distance Vision
far point of vision |
distance beyond which lens will not change its shape (about 20 feet) (flattest point of the lens)
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Focusing for Distance Vision
emmetropic eye |
normal, healthy eye
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Focusing for Close Vision
(Less than 6 feet) accommodation of lens |
lens shape becomes more convex, light rays bend more sharply, shorter focal length for the closer object (ciliary muscles for lens)
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Focusing for Close Vision
(Less than 6 feet) near point of vision |
shortest distance for focusing (maximum convexity of lens); about 8-10 inches; gets worse with age
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Focusing for Close Vision
(Less than 6 feet) presbyopia |
poor close vision in elderly; inelasticity of the lens
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Focusing for Close Vision
(Less than 6 feet) accommodation of pupils |
constriction of pupils; better focus, less divergent rays (constrictor muscles of iris)
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Focusing for Close Vision
(Less than 6 feet) convergence of eyes |
eyes rotate medially to keep image on center of the retina (medial rectus muscles of eyeballs)
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Vision Problems Related to Refraction
myopia ("nearsighted") |
distant objects are blurred; distant objects are focused in front of the retina, rather than directly on it
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Vision Problems Related to Refraction
myopia ("nearsighted") causes |
eyeball too long; lens too strong
concave lens can correct light before eye |
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Vision Problems Related to Refraction
hyperopia ("farsightedness") |
close objects are blurred; close objects are focused beyond the retina, rather than directly on it
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Vision Problems Related to Refraction
hyperopia ("farsightedness") Causes |
a. eyeball too short; poor refraction of a lens
b. convex lens can correct light before eye |
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Vision Problems Related to Refraction
astigmatism |
- blurry images at all distances; unequal curves on lens and/or cornea, creating discontinuous image on the retina
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