Wireless lightbulb from Tesla coil

[musicboy]

Hi all
I've seen demonstrations where a strip lIght or lightbulb has been lit wirelessly from a Tesla coil, and was just wondering how this works. The bit I don't understand is how there is a voltage across it's two contacts, since surely all the air around it is being charged equally.
Thanks.

 

[Arouse1973]

Hello
One side of the tesla coil needs to be grounded. The air is conductive enough at such high voltages to allow enough current to light the bulb. Think of the air as invisible wires which become quite conductive at high voltages but you can't see them.
Adam

 

[duke37]

A fluorescent tube contains low pressure gas which emits radiation when it is ionised. This radiation then activates the fluorescent coating.
You do not need to connect to the tube terminals, it is only necessary to put the tube into a strong enough field to ionise the gas. The Tesla coil will do this or high voltage power lines. It can be useful to find standing waves on transmitter feeders.

You will not get an incandescent bulb with a resistive filament to light in this way.

 

[Arouse1973]

Just by holding the bulb no you won't but if you have a good enough connection to ground and you are touching the other terminal I think you can.
Adam

 

[Gryd3]

Just by holding the bulb no you won't but if you have a good enough connection to ground and you are touching the other terminal I think you can.
Adam

I think we should classify which bulb you are talking about.

Incandescent bulbs, I say no way. They may be able to pick up voltage by grounding one terminal and having an antenna or person touch the other... but they require quite a bit of current to actually light.
The little fluorescent bulb replacements, sure. As mentioned above, the phosphorous coating can get excited simply by being close enough to the field emitted by the Tesla Coil. (Or other HV source, like power transmission lines.)
LED Bulbs, again, I say no way due to the same reasons as the incandescent. That said, with special modifications to the 'receiving' part of this experiment, I'm sure you can gather enough of the field to produce a small enough current to cause the incandescent or led to lightly glow or light intermittently.

Does anyone remember those little plasma balls? When I had one, I was able to hold a fluorescent tube in one hand, and touch the plasma globe with the other, and the tube would begin to glow.

 

[Arouse1973]

Really ok. Lets leave it at that then.
Adam

 

[Bradley]

My coil will light a t8 flourecent at 4ft