- Opacity can be caused by various factors, such as absorption, reflection, and scattering.
- An entirely opaque substance reflects and absorbs all incident light, with no transmission or scattering.
- When light strikes an interface between two media, some light is reflected, some is absorbed, and some is scattered:
- The remaining light undergoes refraction and is transmitted through the second medium.
- Opacity therefore measures the ability of the second medium to obstruct light.
- An opaque object is neither transparent (allowing all light to pass through) nor translucent (allowing some light to pass through).
- Opacity of some media varies with the wavelengths of light. For example, certain types of glass are transparent in the visual range but mostly opaque to ultraviolet light.
Related diagrams
Each diagram below can be viewed on its own page with a full explanation.
- Opacity refers to the extent to which an object or surface hinders or blocks light from passing through and so obstructs light from reaching objects or space beyond.
- Opacity can be caused by various factors, such as absorption, reflection, and scattering.
- An entirely opaque substance reflects and absorbs all incident light, with no transmission or scattering.
- When light strikes an interface between two media, some light is reflected, some is absorbed, and some is scattered:
- The remaining light undergoes refraction and is transmitted through the second medium.
- Opacity therefore measures the ability of the second medium to obstruct light.
- An opaque object is neither transparent (allowing all light to pass through) nor translucent (allowing some light to pass through).
- Opacity of some media varies with the wavelengths of light. For example, certain types of glass are transparent in the visual range but mostly opaque to ultraviolet light.