How Everything Works
How Everything Works How Everything Works

Question 641

When light hits an object, how do we recognize the color? — CM, Levering, PA
White light is a mixture of various light waves with different wavelengths and thus different colors. When white light hits an object, some of the light waves are absorbed while others are not. The light that isn't absorbed may pass through the object or it may be reflected in a new direction. The light that you observe coming from the object is this transmitted or reflected light. If the light that you see doesn't include the same mixture of wavelengths that first hit the object, you won't see this light as white. Instead, you'll see it as colored. If the light you see contains mostly long wavelengths of light, you'll see it as red. If the light contains mostly short wavelengths of light, you'll see it as blue or violet. The wide range of colors that objects have comes from subtle differences in the wavelengths of light they absorb. However, when an object is illuminated with colored light, the light that it transmits or reflects may be altered. After all, it can't transmit or reflect a light wave that never hit it in the first place. Even variations in "white" light can affect an object's color—makeup looks different in incandescent "white" light than it does in fluorescent "white" light because those illuminations contain different mixtures of light waves.

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