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ch 30 vocabulary
| Question | Answer |
|---|---|
| lens | a piece of glass(or other transparent material) that can bend parallel rays of light so that they cross,or appear to cross,at a single point. |
| converging lens | a lens that is the thickest in the middle,causing parallel rays of light to converge to a focus. |
| convex lens | middle,causing parallel rays of light to converge to a focus. |
| diverging lens | a lens that is the thinnest in the middle and that causes parallel rays of light to diverge |
| concave lens | a lens that is the thinnest in the middle and that causes parallel rays of light to diverge |
| principal axis | the line joining the centers of curature of the surfaces of a lens |
| focal point | for converging lens the point at which a beam of light parallel to the principal axis converges for a diverging lens the point from which such a beam appears to come |
| focal plane | a plane passing through either focal point of a lens that is perpendicualr to the principal axis. for a converging lens, any incident parallel beam of light converges to a point somewhere on a focal plane. for a diverging lens, such a beam |
| 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 light from the object does not actually come to a focus |
| ray diagram | a diagram showing rays that can drawn to determine the size and location of an image formed by a mirror or lens |