18.3 Key Concepts What three types of materials affect the behavior of light?

1. 18.3 Key Concepts • What three types of materials affect the behavior of light? • How does light behave when it enters a new medium?

2. nothing Without light _______________ is visible. You can see reef animals through water because light ___________ through the water between the reef and your _________. passes eyes

3. Light and Materials • How light behaves when it strikes an object depends on many factors, including the __________________ the object is made of… • Materials can be… • ______________________ • ______________________ • ______________________ material transparent translucent opaque

4. Light and Materials transmits A transparent material _____________ light, which means it allows __________ of the light that strikes it to pass through it. . most The water where the fish and coral live is transparent.

5. Light and Materials While riding on a bus, you can see buildings and trees outside because the bus ______________ are transparent. . windows

6. Light and Materials scatters A translucent material ____________ light. As a result, the objects you see through it look ____________ or may lack _______________; as opposed to clear or distinct. detail fuzzy

7. Light and Materials absorbs An opaque material either ___________ or ______________ all of the light that strikes it. __________ materials are opaque. An opaque object does ______ ____________ any light to pass through it. reflects Most not allow

8. Interactions of Light • When light strikes a _________ medium, the light can be… • __________________ • __________________ • __________________ • If transmitted, or _________________, it can be refracted, polarized, or scattered. new reflected absorbed transmitted passed through

9. Interactions of Light Recall that when light encounters matter, some or all of the energy in the light can be ________________ to the matter. Just as light can affect matter, _____________ can affect _____________. transferred matter light

10. Interactions of Light Reflection An ____________is a ____________ of an object formed by reflected (or refracted) waves of light. Regular reflection occurs when parallel light waves strike a surface and reflect all in the __________ _____________________ Diffuse reflection occurs when parallel light waves strike a ____________, uneven surface and reflect in many ________________directions. copy image same direction rough different

11. Interactions of Light Which example is regular reflection? And diffuse reflection? regular diffuse

12. Interactions of Light Refraction A light wave can refract, or ____________, when it passes at an ______________ from one medium into another. Refraction makes underwater objects appear _______________ and larger than they really are. Refraction can also make an object appear to _____________ at the surface of the water. bend angle closer break

13. Interactions of Light Because the light bends, the image you see appears to be bent as well.

14. Interactions of Light Refraction can also sometimes cause a ______________, a false or distorted image. • Mirages occur because light travels ______________ in ________ air than in cooler, denser air. • Refraction causes some of the light to follow a __________________ path, rather than a straight path to the ground. • Light that reaches your eyes after traveling in this manner can look as if it was reflected from a layer of ____________________. mirage faster hot curved water

15. before Light is refracted by hot air ___________ it reaches the ground

17. Interactions of Light Polarization Light with waves that vibrate in only ________ ___________ is polarized light. Polarized light may occur when light reflects from a ________________ flat surface, such as a… • __________________ • surface of a _______________ one plane nonmetallic window lake

18. Interactions of Light Polarization • Horizontally polarized light reflects more ____________ than the rest of the sunlight, producing a _________________ • Polarized _________________ have vertically polarized _______________ to block the horizontally polarized light. strongly glare sunglasses filters

19. Horizontal polarizing filter Vertical polarizing filter Horizontal wave is blocked Vertical wave is blocked Vertical wave passes through filter. Interactions of Light A vertical polarizing filter blocks light that is __________________ polarized. horizontally

20. redirected Scattering In scattering, light is ____________________ as it passes through a medium. • Most of the particles in the atmosphere are very _____________. • Small particles scatter ________ wavelength _________ light more than light of longer wavelengths. • Blue light is scattered in all directions more than other colors of light, which makes the _________ appear blue. small shorter blue sky

21. Interactions of Light sunset A scattering effect reddens the sun at ___________ and ______________ • When the sun is close to the horizon, sunlight travels ____________________ through the atmosphere. • By the time the sunlight reaches your eyes, most ______________-wavelength light has been scattered. • The remaining light consists mostly of ____________ wavelength reds and oranges sunrise farther shorter longer

22. Assessment Questions • How do polarized sunglasses reduce glare? • by scattering light as it passes through the glasses • by providing a smooth surface that light can reflect off • by absorbing all light • by blocking horizontally polarized light

23. Assessment Questions 2. An opaque material passes light through but scatters the light so that objects do not look clear. TrueFalse

24. Assessment Questions 3. The following picture is an example of… • Reflection • Refraction • Polarization • Scattering