Everyday Science

Why do you have to "charge" glow-in-the-dark toys with a light?
Answered by Planet Green
  • Planet Green

    Planet Green

  1. To make most glow-in-the-dark products glow, first you have to "charge" them by holding them up to a light for about 10 minutes. The reason they glow is because they contain phosphors; these are substances that radiate visible light once energized. The phosphors in glow-in-the-dark toys - - often zinc sulfide and strontium aluminate - - can be energized by regular light. Some objects glow even without charging, like the painted hands of some watches. The phosphors in these objects have been premixed with a radioactive substance that continuously energizes the phosphor.

    More answers from Planet Green »



Still Curious?
  • How can you make an Altoids tin into a flashlight?


    Answered by Science Channel

  • What other privacy concerns do biometric systems raise?


    Answered by Discovery Channel

  • How does Google use technology to help the world a better place?


    Answered by Megan Smith