photochromism

/ˌfoʊtoʊˈkroʊmɪzəm/
noun
  1. The property of a material to change color reversibly when exposed to light, especially ultraviolet light.
    • Photochromism is the science behind eyeglasses that darken in sunlight.
    • Researchers are studying photochromism to create smart windows that control heat and light.
    • The photochromism of certain minerals makes them appear different colors under various lighting conditions.
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