Liquid crystals like these are common ingredients in mood rings. Molecules in a liquid usually don’t order themselves the way molecules in solids do. But, these cholesterol-like liquid-crystal molecules can loosely stack into layers even in a liquid phase. In mood rings, the temperature of your hand—not your mood—heats up or cools down the liquid crystals and changes the spacing between the crystal layers. The spacing affects how light interacts with the layers, and therefore, changing the spacing leads to shifts in color.
Ryan Latterman, a professor at Wisconsin Lutheran College, didn’t bust open a mood ring to make this gooey mess. His students accidently spilled the liquid crystals on a lab bench during class. When Latterman stirred around the liquid-crystal goo, the warmth from his finger disrupted the way the layers stacked, causing the color change.
Credit: Ryan Latterman and his Chemistry 168 class
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