The color of an object is directly related to which wavelengths of visible light it reflects, absorbs, or transmits:
- Reflection and absorption
- When white light (which contains all visible wavelengths) hits an object, some wavelengths are absorbed and others are reflected.
- The wavelengths that are reflected (or transmitted, if the object is transparent) are the ones our eyes detect, and they determine the object’s perceived color.
- Example: A red apple reflects wavelengths around ~620–750 nm (red) and absorbs most others.
- Selective wavelength interaction
- Black objects absorb nearly all visible wavelengths, reflecting very little light.
- White objects reflect most wavelengths fairly equally, so we perceive them as colorless (white).
- Colored transparent materials (like blue glass) transmit certain wavelengths and absorb the rest.
- Special cases
- Metallic surfaces reflect light in a way that can give shiny or mirror-like appearances.
- Structural colors (like in butterfly wings or peacock feathers) come from microscopic patterns that interfere with light, rather than pigments.
In short, an object’s color is the set of visible wavelengths it sends to your eyes, whether by reflection, transmission, or scattering.