How Does "glow in the Dark" Work?


Quick Answer

Photoluminescence is a glow produced by visible or invisible light. According to Physics.org, this glow-in-the-dark phenomenon works by way of phosphor, a type of chemical that absorbs energy and re-emits it as light. Two of the most commonly used phosphors for glow-in-the-dark products are zinc sulphide and strontium aluminate, because they re-emit energy for a long period of time.

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How Does "glow in the Dark" Work?
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Full Answer

The phosphors can be mixed with plastic or ink to create glow-in-the-dark stars or prints, or to increase the visibility of emergency exit signs in public buildings. When light hits a glow-in-the-dark object, the incoming photons (packets of light) excite the phosphor molecules. These molecules slowly release the energy they have stored by giving out photons, creating a dim glow. Different phosphors release energy at different rates - the more slowly they release energy, the longer they will glow, as Physics.org explains.

Photoluminescent products can be found anywhere, and their glow-in-the-dark pigments can be produced in a multitude of different colors. However, the human eye is more sensitive to green light, making the green glow of some products appear brighter. For this reason manufacturers generally favor the color green. This is also why night-vision goggles typically color things in green, according to Physics.org.

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