[Phys-L] Re: Electroluminescence Demo

[ludwik kowalski <kowalskil@MAIL.MONTCLAIR.EDU>]

The fact that the lamp connected to 110 V produces more light than when
an electrolytic cell is inserted in series is not surprising. Did you
measure the cell voltage? The glow on the electrons should depend on
that voltage only; presence of the 75 W light lamp is probably
irrelevant.

Here is my guess about the mechanism; I have observed something of that
kind recently (at considerably higher voltages and with a different
electrolyte). Suppose electrodes are coated with thin layers of gasses,
for example, H2 and O2 due decomposition of water. The resistance
through the liquid electrolyte is much lower than the resistance
through a gas. Therefore the field in the gas might become strong
enough to produce the glow discharge. Increase the voltage and you
might see more light due to that glow discharge. Have a good fuse to
stop possible arcing at some high voltage.

Ludwik Kowalski

On Dec 18, 2005, at 11:35 PM, Brian Whatcott wrote:

> Mix 1 tablespoon baking soda in 1 pint water.
> Cut two electrodes from an aluminum pie dish
> Place the elctrodes on opposite sides of a jam-jar.
>
> Connect the electrolytic cell in series with a 75 watt lamp
> to a 120 volt AC line supply - or better, through a 1:1
> isolation transformer.      Care!
>
> The light quickly dims.
> In a dark room, the electrodes glow.
>
> See  <http://home.earthlink.net/~lenyr/borax.htm>
>
> What is the mechanism?
>
>
> Brian Whatcott    Altus OK    Eureka!
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