I was wondering if you could tell me what the hands in my watch are
made of, which makes them glow in the dark. I was told by my chemistry
teacher that they are now using a new substance in these watch hands to make
them glow. I was wondering if you could please help me out??? What is this
substance?
I heard it was radium, but I could be wrong.
I always thought it was radium, but apparently that was the bad ol’ days. According to this site
http://www.wonderquest.com/GlowInDark.htm
it is a substance called phosphor.
Your personality.
(Just kidding. I’m not that good a judge of character.)
Many watches have tritium dials. If you look at the bottom of the dial and it says “T 25” or “T~25”, then it has 25 microcuries or less than 25 microcuries of radioactivity provided by tritium, respectively. I’m not sure of the half-life, but I think it’s about 12 years.
My newest watch (bought in 2000) has a Super Luminova dial. This dial is not (AFAIK) radioactive, puts out more light, and should last longer than tritium.
[list][list][list][list][list]Chernobyl?
…:eek:…
Word of Wisdom #457.
If it glows in the dark, don’t eat it.
Obligitory link to HowStuffWorks:
To sum up that article, chemicals called phosphors are painted on the hands of your watch. When light strikes them, the electrons in the phosphors get excited. They jump up to a higher energy state.
When you turn off the light, there’s nothing holding the electrons up, and they eventaully crash down to their initial state… being energetic little electrons, they give off a little green glow as they fall. This can take several hours for the phosphors in some high-end watches; inexpensive phosphors used in cheacper watches, toys and such use up all their “excited electron energy” in just a few minutes.
Tritium (a heavy form of hydrogen, with two neutrons) is a radioactive material sometimes mixed in with phosphors to create a permanent glow for some specialty watches. Tritium’s slow radioactive decay keeps the phosphor electrons constantly excited, so the watch never has to be exposed to light.