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Noob question

Discussion in 'General Electronics Discussion' started by CrimpJiggler, Oct 9, 2012.

  1. CrimpJiggler

    CrimpJiggler

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    Oct 8, 2012
    I've been experimenting with a AA battery to get a better understanding of practical electronics. I made a strip of aluminum foil and I held one end of the strip to the positive terminal and the other end to the negative terminal (I know that aluminum is an excellent conducter so a circuit with such low resistance like this should cause the battery to heat up), I felt the foil to the terminals with my fingers and instantly I felt a burning sensation which within a second or two got so intense I had to let go. The battery itself didn't heat up but my fingers felt like they were burning.

    What is the cause of this burning sensation? At first I thought that maybe some of the current takes a bit of a detour through my skin but my fingers were dry and if I'm not mistaken, skin has very low conductivity. Also, I broke the circuit by tearing the strip in half, then I completed the circuit by holding the two ends of the wire together with my fingers and I got no burning sensation at all, not even a shock. This burning sensation only happens when I hold both the aluminum to the terminals of the battery. Can anyone explain whats going on here?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    You heated up the aluminium foil.
     
  3. CrimpJiggler

    CrimpJiggler

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    Oct 8, 2012
    The aluminum foil doesn't get hot. Heres the battery:
    [​IMG]
    as you can see, its just a 1.5V AAA battery with some aluminum foil blu taced to the terminals. If I put my fingers on each terminal then complete the circuit, my fingers start to burn. If I just complete the circuit by holding the broken ends of the aluminum foil together with my fingers, I feel no heat. Its not the aluminum foil thats heating up, theres something else going on here. Try it yourself and you'll see how rapidly the burning sensation builds up.
     
  4. BobK

    BobK

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    Jan 5, 2010
    Most likely they are not making contact with the battery terminals when you are not pushing on them with your fingers. Try just connecting the two end of the foil and holding it for several minutes. If nothing gets hot, there is no current flowing.

    Bob
     
  5. CrimpJiggler

    CrimpJiggler

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    Oct 8, 2012
    Yeah thats a possibility. I just blu-tacked the leads together, if you're theory is correct then the battery will stay cool.
     
  6. CrimpJiggler

    CrimpJiggler

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    Oct 8, 2012
    You were right. The battery didn't heat up at all.
     
  7. CiaranM

    CiaranM

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    May 19, 2012
    ha ha this reminds me of when I started out with elecs. I got one bit of metal on one end going to other end. 'Hey, this gets pretty hot!'
    The reason for this is simply that the battery is being short-circuited (minimal resistance connection from one end to the other) and power isn't being dissipated by a circuit; rather, the battery is having to deal with all the electrons. This short-circuit current (Is) creates heat...
    don't do this for too long, wouldn't want a battery-related facial reconstruction to happen (BANG!)
     
  8. donkey

    donkey

    1,286
    56
    Feb 26, 2011
    an experiment siliar to this was conducted a while back early half of the 1800's. if you use 2 different materials to short the battery then you can make a heat pump. have fun trying that next
     
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