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What Determines Whether a Material Is Transparent or Opaque?

Transparent, translucent and opaque are terms used to describe how well an object or material allows light to pass through it. Along with light, color can pass through some objects and materials. The terms are also useful for other descriptions. For example, when an administrator is open about policies, the administrator is transparent. Artists also use these terms to describe the mediums they use to create their art.

Transparent
- Materials that are transparent allow a lot of light to pass through, like the glass on this clock.
  
  An object that is transparent can be seen through completely. The material that is transparent allows light to pass completely through it, and it remains the same color when it passes through the other side. The molecules in a transparent material are less dense than the molecules in translucent or opaque materials.
Opaque
- Opaque materials allow no light to pass through, like the black glass of this bottle.
  
  An opaque material has a more dense pattern of molecules. Opaque materials do not allow light to pass through them. The light is either reflected by the material or absorbed by it. If the light is absorbed by the opaque material, the energy is converted into heat.
Translucent
- These gummy bears are translucent, allowing light to pass through without being completely see-through.
  
  Translucent materials are between transparent and opaque materials. They allow some of the light and color to pass through the molecules, but not all of it. The molecules in translucent materials are not as dense as those in opaque materials but are less dense than the molecules in transparent materials.
Examples
- Transparent materials include air, clear water, clear glass, plastic wrap, laminating material and other materials that can be seen through completely. If you look through a material and you can see all of the light and colors on the other side, it is a transparent material. Translucent materials include tissue paper, wax paper, paper towels and most plastic lids for drinking cups. Translucent materials allow the light to pass through, but not much of the color is visible. Opaque materials include construction paper, cardboard, felt, styrofoam and aluminum foil. These materials do not allow any of the light or color to pass through them because the molecules are too dense.
Why is Something Transparent?
- When it comes to an object's transparency, the amount of light that can pass through the object is the single determinant. Therefore, the more light that is passing through the object the more transparent that object is. On the opposite end of the spectrum, if no light is passing through an object, it is completely opaque.

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