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Roadside Pencil Light

Discussion in 'General Discussion' started by <exile>, Feb 24, 2008.

  1. <exile>

    <exile> Padawan Learner

    <embed src="http://www.metacafe.com/fplayer/726251/turn_a_pencil_into_a_light.swf" wmode="transparent" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" height="345" width="400">
    Turn A PENCIL Into A LIGHT ! - video powered by Metacafe
  2. Tracy

    Tracy Insatiably Curious Moderator Founding Member

    That's great in case of emergency!

    Thanks for sharing!

    Hmmm... I wonder how strong the battery has to be to make this work?
  3. BigO01

    BigO01 Monkey+++ Founding Member

    75% of the people today would do much better making sure once every 6 months they have a charged flashlight in thier car with an extra set of batteries .

    It's a neet thing to know but since you're burning the pencil "lead" how many people would burn themselves trying it ?

    Or worse blow up the car battery .
  4. Tracy

    Tracy Insatiably Curious Moderator Founding Member

    I was thinking "science experiment" and wondering if the same effect could be achieved with a smaller battery.
  5. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Yes, it could, but. The demo was done with a 12 volt car battery. I would not expect a (say 9 volt) to glow as brightly, and being MUCH smaller, the glow wouldn't last as long. The key element is the ability of the pencil "lead" to conduct the amperage. A couple things stand out in the vid, one of which is that it is pretty high hazard from burning or igniting something, not to mention burned fingers. I don't know what the resistance of pencil lead is, but looks like it might be low enough to behave nearly like a dead short, dunno how long any given battery might last in that service. All that said, it could be a life saver somewhere along the line. (NB, it might be also used to start a fire in a pinch.)
  6. monkeyman

    monkeyman Monkey+++ Moderator Emeritus Founding Member

    Knew a similar trick from a youth mis spent enouph to associate with folks spending a lot of it locked up figureing out how to light smokes with no lighter in jail. They would strip the wood back on a pencil leaving the lead then short it in a light outlet and ignite the eraser then use it to light a smoke.
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