The absorption and the selective refraction of light the color of objects
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The document discusses the selective absorption and reflection of light and how it relates to color. 1) Light passing through a medium decreases in intensity exponentially with distance according to the absorption factor α, which depends on the wavelength of light. 2) Objects appear colored because they selectively absorb some wavelengths of visible light while reflecting or transmitting others. 3) The color of objects is due to their ability to selectively absorb and reflect certain wavelengths of visible light, making them appear that color.
The absorption and the selective refraction of light the color of objects
- 2. THE SELECTIVE ABSORPTION AND REFLECTION OF LIGHT
- 3. The selective absorption and reflection of light. The color of objects CONTENT 1. light absorption Definition The law of light absorption The selective absorption of light 2. Selective reflection (diffusion) of light. The colors of objects 3
- 4. The selective absorption and reflection of light. The color of objects 1.The light absorption 4 a) Definition The phenomenon in which a medium decreases the intensity of the light beam going though it is called light absorption. d d
- 5. The selective absorption and reflection of light. The color of objects 1.The light absorption 5 The intensity I of a monochromatic light beam after going through an absorptive medium decreases as an exponential function of the distance it travels: In which: I = intensity of transmitted light (cd) I0 = intensity of incident light (cd) is called absorptive factor d I = I0e-αd b) The law of light absorption
- 6. The selective absorption and reflection of light. The color of objects 1.The light absorption c) The selective absorption of light 6
- 8. The selective absorption and reflection of light. The color of objects 1.The light absorption c) The selective absorption of light => Different lights are absorbed differently. In other words, the absorption of light through a medium is selective. => depends on 8
- 9. The selective absorption and reflection of light. The color of objects 1.The light absorption • Objects which don’t absorb any light in a part of spectrum are said to be nearly transparent with that part of spectrum • Objects which don’t absorb the visible light are called non-colored transparent objects • Objects which absorb selectively visible light are called colored transparent objects • Black objects are objects which can absorb all visible light 9
- 10. The selective absorption and reflection of light. The color of objects 2. The Selective reflection (diffusion) of light. The colors of objects For some objects, the ability to reflect (or deffuse) light depends on the wavelength of incident light. Some objects reflect (or deffuse) strongly lights of long wavelength, but reflect (or deffuse) weakly lights of short wavelength. It is called the selective reflection (or deffusion) of light 10 Wavelength (nm) Ratio (%) 357 27 500 44 600 72 700 83 800 89 1000 90 The ratio of the intensity of reflected light and incident light from the smooth surface of a copper plate
- 11. The selective absorption and reflection of light. The color of objects 11 Objects appear to have colors since they are able to selectively absorb and reflect certain wavelengths of visible light
- 12. The selective absorption and reflection of light. The color of objects Summary • After going through a medium, the intensity of any light……………. As an ………………… function of the …………………… • Objects ……………..and……………………………lights…………………so that they appear to have…………… • Explain the following experiment. 12
- 13. The selective absorption and reflection of light. The color of objects 13