Optics
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Colored lights - color of objects
Colors of objects
1) Object illuminated by white light
During a diffusion, an object receives light and then sends back a part of it in all directions.
The color possessed by objects depends on the light they diffuse: its color is the same as the color diffused.
For instance, an object diffusing only red lights, sends back red lights and absorbs all other colored lights: its color seems to be red.
Conversely, we can deduce from the color of an object the colors it absorbs: for instance, a green object absorbs all colored lights except the green ones that are diffused.
2) Object illuminated by a colored light
The color of an object depends on the color of light by which it is illuminated
If an object receives only lights that are absorbed, it seems to be black
For instance:
- A red object ( in white light ) illuminated by a green light seems to be black.
- A red object illuminated by a blue light seems to be black.
- A red object illuminated by a cyan light ( mix of green and blue lights ) seems to be black.
If an object receive a light that it doesn't absorb, it keeps the same color as with white light.
For instance:
- A red object ( in white light ) illuminated by a red light seems to be red.
- A red object ( in white light ) illuminated by a magenta light ( mix of red and blue lights ) seems to be red.
- A red object ( in white light ) illuminated by a yellow light ( mix of red and green lights ) seems to be red.
| Science class |
| Optics lessons |
Light sources - Types of light sources - Why can we see objects ? Propagation of light - Rectilinear propagation of light - Beams of light - Speed of light - Light and distances Shadows, lunar eclipses and phases of the moon - Formation of shadows - The Moon and eclipses Colored lights - color of objects - Decomposition of white light - Colored lights - Color of objects Image formation - Thin lenses - Thin converging and diverging lenses - Image formation by thin lenses - Vision and eyes |
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