Reflection and refraction
- 1. Ch 17 Reflection and Refraction
- 2. Reflection Law of reflection - when a light ray strikes a reflecting surface, the angle of reflection equals the angle of incidence
- 3. Regular vs Diffuse Reflection If the beam of light falls on a smooth surface the rays undergo regular reflection (parallel rays reflect parallel) If the beam of light falls on a rough surface, the rays undergo diffuse reflection (parallel rays do not reflect parallel)
- 4. Why is it harder to see when driving at night after it has rained? Answer: Because the wet road is a smooth surface and very little light is reflected back to our eyes
- 5. Are the pages of your book smooth or rough? Answer: They are rough If they were smooth, there would be a lot more glare and it would be harder to read.
- 6. Refraction Refraction- the change in speed and direction of light at the boundary between 2 media. Snells Law: ni sin øi = nr sin ør When light travels from a less optically dense medium into a more optically dense medium, the speed is reduced and the angle of refraction is smaller than the angle of incidence. V= c/ nr
- 7. Total internal reflection occurs when light passes from a more optically dense medium to a less optically dense medium at such an angle that the angle of refraction is 90 degrees. Crtitical angle - angle of incidence that causes total internal reflection
- 8. Dispersion - separation of light into the spectrum of colors Red light travels fastest; it bends the least; has the smallest index of refraction Violet light travels the slowest, it bends the most; has the largest index of refraction
- 9. Rainbows A rainbow is formed when sunlight is dispersed by water droplets.