Colors change in light because the colors we perceive are determined by how objects absorb, reflect, and transmit different wavelengths of light. Changes in the type and intensity of the light source will therefore alter the wavelengths that are present, and consequently, the colors we see.
Here's a breakdown of the process:
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Light Source Matters: Different light sources emit different spectra of light. For example, incandescent bulbs produce more red and yellow light, while fluorescent lights produce more blue and green light. Sunlight is a relatively balanced spectrum, containing a wide range of wavelengths.
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Object Interaction: When light strikes an object, the object's surface absorbs some wavelengths and reflects others. The wavelengths that are reflected are what we perceive as the object's color.
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Perceived Color: The perceived color is the result of the interaction between the light source's spectrum and the object's reflective properties.
Let's illustrate with an example:
Imagine a red apple. It appears red because its surface absorbs most wavelengths of light except those in the red part of the spectrum, which it reflects.
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Under Sunlight: Sunlight contains a good amount of red light. The apple reflects the red light, and we see a vibrant red apple.
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Under a Blue Light: A blue light source emits mostly blue wavelengths. There is very little red light for the apple to reflect. The apple will absorb most of the blue light and reflect very little, so it may appear dark or even blackish, not red.
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Dim Light: If the light is dim, regardless of the color composition, the apple will appear as a darker, less saturated shade of red simply because there is less light to be reflected.
| Light Source | Dominant Wavelengths | How the Red Apple Appears |
|---|---|---|
| Sunlight | Balanced | Vibrant Red |
| Incandescent Bulb | Red/Yellow | Slightly Warmer Red |
| Fluorescent Light | Blue/Green | Duller, Less Intense Red |
| Blue Light | Blue | Dark/Blackish |
| Dim Light (Any Color) | Reduced Intensity | Darker, Less Saturated Red |
In essence, the perceived color is a combination of:
- The wavelengths of light present in the light source.
- The object's inherent properties of absorption and reflection.
Changing either of these factors will change the perceived color.
