by Ernest Capraro

Created on: September 28, 2007

Perhaps the similarity in names is to blame for all the confusion. Both do begin with "trans-" after all. And both transparent and translucent objects allow light to pass through them, which is the reason for "trans-" in their names. The difference arises in how light is passed through the object in question.

In a transparent medium, light can travel through from one side to the other unobstructed. This means that the atoms/molecules within the material do not absorb or scatter the light. Because the light passes through without hindrance, it can reach our eyes to show a clear image of what is on the other side. It may be helpful to remember that you can PEER through a transPAREnt object.

Most materials are only transparent to certain wavelengths of light. Most often we are interested in those that are transparent to visible light - window glass, plastics for various purposes (including transparencies - guess how they got that name), and even air. Sometimes though, we may want a material that is transparent to UV light (quartz is, glass is not) or other regions of the electromagnetic spectrum. In those cases, the materials required may be quite different.

Translucent mediums do allow light to pass through them, but they absorb, scatter, and diffuse the light, so that the light no longer follows a coherent path. Instead, the light emerges from the material in all directions, having traveled varying path lengths, and images are not transmitted. When light passes through a translucent object, the visual perception is that the object glows. This can be a pleasing effect, as with a crystal of orange calcite (a translucent mineral) with a light bulb inside or behind. Since a transluCENT objects can appear to glow, try remembering that they appear to glow from the CENTER.

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