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Light a bulb without a closed circuit

Discussion in 'Electronic Design' started by [email protected], Mar 31, 2009.

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  1. Guest

    I was recently reading a paper about charges on the surface of circuit
    elements, and how circuits settle to a stead-state of charge flow.
    They mentioned in passing an experiment I have never seen, and I was
    wondering if anyone here has heard of it:

    They mentioned that they could light a bulb in a non-closed circuit,
    by connecting one end to a battery and a bulb. Obviosuly it was not
    usign a group loop or external induction, but was meant to be setup in
    a way that the small transient could actually be seen. They even had
    it so that if you bent the wire you could make bulbs light up because
    you would be temporarily causing non-uniform charge areas that have to
    flow to steady state (no current). Does anyone know specifically what
    they did?

    The only ones I have seen are where you put a capacitor and a globe in
    a series circuit and connect it to a battery and make the globe light
    when you move the bulb/wires close to the battery.
     
  2. Martin Brown

    Martin Brown Guest

    More impressive still vertical fluorescent tubes will glow quite nicely
    when you pass under an EHT power line. There was a nice art installation
    of hundreds of them plonked in a field under supergrid pylons a few
    years back in the UK. Made the front page of several papers.

    Regards,
    Martin Brown
     
  3. whit3rd

    whit3rd Guest

    With RF, it's easy. Put a dead fluorescent lamp in your microwave
    oven next time you heat up the coffee, or connect rabbit-ear
    antennae to an incandescent lamp and stand next to a
    transmitter.
     
  4. Tim Williams

    Tim Williams Guest

    Of course, all of these phenomena can be analyzed under normal rules
    when you include parasitic capacitance to ground, which can be empty
    space if nothing else; for instance, as I recall the Earth is around
    1uF simply by being a conductive sphere.

    Tim
     
  5. ZACK`

    ZACK` Guest

    you can light a up a dead fluo tube say 40watt with a
    car ignition coil by osillating it like ccfs
     
  6. Martin Brown

    Martin Brown Guest

    It is more fun if the ignition coil is used to drive a Tesla coil - then
    you really can get some interesting illumination effects from vacuum tubes.

    Regards,
    Martin Brown
     
  7. MisterE

    MisterE Guest

    The experiment I was refering to was able to capture the slight current that
    is caused when you connect a peice of metal to a potential, there was no
    voltage 'field' involved.
     
  8. MisterE

    MisterE Guest

    No it was without any sort of induction or field, it was purely by capturing
    the tiny movement of very small amount of charge in a wire when you connect
    it to any voltage, like how you can measure static electric field that is
    different in different parts of the same circuit, as charge accumulates
    unevenely even at steady state.
     
  9. whit3rd

    whit3rd Guest

    I'm not sure what that means. There is an old experimental technique
    using a 'ballistic galvanometer' that can capture charge transfer
    on contact (like when your shoes rub the carpet and a static
    charge transfers). There are very real fields involved there, of
    course.
    All material objects generate and shape electric fields.

    "small amount of charge in a wire when you connect it" could cover
    ANY kind of electric light.
     
  10. whit3rd

    whit3rd Guest

    Not all. To explain radiation (like, electric energy more than one
    wavelength away from the antenna) requires Maxwell's equations,
    not just the "usual" Kirkhoff rules.
     
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