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Across 2. To cast or bounce back from a surface 5. Light that is produced by excited molecules or atoms 9. One of the three things you need for sight, the organ that makes sense of the image your eyes see 10. A lens that curves or rounds inward 11. To soak up or take in 15. Lets no light through, objects cannot been seen through it 16. Lets all light pass through so that objects can be seen through it 17. One of the three things you need for sight. An illuminting agent or source, such as the sun, that makes things visible 18. The science dealing with properties of light and vision 20. A transparent substance, usually glass, having two curved surfaces used for magnification or to correct defects in vision

Down 1. One of the three things you need for sight. The organ used for sight 3. Light that is produced by using electricity to ignite mercury vapor 4. A lens that curves or rounds outwards 6. Light that is produced by a heat source 7. A dark image cast on the ground when something intercepts the light 8. Lets some light through, but scatters the rays, so objects cannot be seen clearly through it 12. A narrow beam of light 13. To emit rays, such as rays of light 14. The bending of light rays as they pass through objects with different densities 19. Lets light into the eye, or, a student