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novelty bulb



Greetings,

While shopping at a Target location last week for a low-budget ($20) plasma ball, I noticed another novelty bulb ($4) on the rack. It looks like a regular clear incandescent light bulb, except that in place of a tungsten filament there are electrodes (in the shape of stars and the word "party!") some colored white and some black. The white pigment appears to have been sloppily applied as a paint by a brush, while the black pigment is a uniform coating.

When screwed into a 120V AC socket, the black electrodes glow with a neon hue with a 1mm to 2 mm discharge aura while the white prongs glow pale green with no discharge aura. A closer look at the glass base within the bulb reveals that one of the white/green prongs is not connected to the circuit, and so must glow due to absorption of UV or xrays emitted by the orange electrodes. There are no plasma "streamers' produced.

I find it curious that

1. the discharge glow is produced at such a low voltage, compared to the 2000 volts in a gas tube ballast.

2. the orange glow around the elctrodes is uniform across the length of the 40 mm wide electrode, even though its separation from the other electrode varies from about 4mm to 20mm.

3. there is no discharge 'ray' between the orange electrodes at their point of least (4 mm)separation.

Has anyone else looked at these bulbs?

Thanks,

-Barry Gragg

The Dwight School

NY, NY

Proud Home of the 2002 NYC Science Olympiad Cowabungee and Physics Lab Champs!



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