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ch 30 vocab #1-25

chapter 30 vocabulary #1-12 and #13-25

QuestionAnswer
lens a piece of glass (or other transarent material) that can bend parallel rays of light so they cross, or appear to cross at a single point.
converging lens a lens that is thickest in the middle, causing parallel rays of light to converge to a focus. Also known as a convex lens.
convex lens a lens that is thickest in the middle, causing parallelrays of light to converge or focus. Also known as a converging lens.
diverging lens A lens that is thinnest in the middle and that causes parallel rays of light to diverge. Also known as a concave lens.
concave lens A lens that is thinnest in the middle and that causes parallel rays of light to diverge. Also known as a diverging lens.
principal axis The line jioning the centers of curvature of the surface of a lens.
focal point for a converging lens, the point at which a beam of light pararllel to the principal axis converges. For a diverging lens, the point from which such a beam appears to come.
focal plane converging lens: any incident parallel beam of light converges to a point somewhere on a focal plane.diverging lens: such a beam appears to come from a point on a focal plane.
focal length the distance between the center of a lens and either focal point.
real image an image that is formed by converging light rays and that can be displayed on a screen.
virtual image an image formed through reflection or refraction that can be seen by an observer but cannot be projected on a screen because the light from the object does not actually come to a focus.
ray diagram a diagram showing rays that can be drawn to determine the size and location of an image formed by a mirror or lens.
eyepiece lens of a telescope closest to the eye; enlarges the real image formed by the first lens.
objective lens in an optical deviceusing compound lenses, the lens closest to the object observed.
cornea the transparent covering over the eyeball.
iris the colored part of the eye that surrounds the black opening through which light passes. The iris regulates the amount of light entering the eye.
pupil the opening in the eyeball through which light passes.
retina the layer of light-sensitive tissue at the back of the eye.
farsighted term applies to a person who has trouble focusing on nearby objects because the eyeball is so short that images form behind the retina.
nearsighted term applies to a person who can clearly see nearby objects but not clearly see distant objects. the eyeball is elongated so that images focus in front of rather than on the retina
astigmatism a defect of the eye caused when the cornea is curved more in one direction than in another.
aberration distortion in an image produced by a lens.
fovea the center of sharpest vision on the retina
blind spot the spot on the eye where the optic nerve takes blood in and out of the eye, and information to the brain.
accomodation when the ciliary nerve squeezes the lens in the eye to accomodate for distance changes.
Created by: imgirl13