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atom physics lesson

Optics

Free online optic lesson for elementary school,  middle school and high school.
chemistry high school
 




















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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.
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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.
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