Plasma ball electric shock mystery

[Herbert Cheung]

Plasma ball has a high voltage. Why don't we get an electric shock when we touch it?

 

[berkeman]

Plasma ball has a high voltage. Why don't we get an electric shock when we touch it?

Glass is an insulator.

 

[Herbert Cheung]

Oic @berkeman
So why is the plasma thread attracted to my hand when we touch it?

 

[berkeman]

Oic @berkeman
So why is the plasma thread attracted to my hand when we touch it?

I believe it's because of the extra parasitic capacitance that your hand presents when you touch the glass globe, but I'm not sure. Can you post links to the reading you've been doing about them? Have you seen if Wikipedia has a good introductory article on them?

 

[anorlunda]

It's actually a very interesting question. The answer seems to be that your finger gets RF energy.

Placing a finger tip on the glass creates an attractive spot for the energy to flow, because the conductive human body (having non-ohmic resistance of about 1000 ohms at room temperature) is more easily polarized than the dielectric material around the electrode (i.e. the gas within the globe) providing an alternative discharge path having less resistance. Therefore, the capacity of the large conducting body to accept radio frequency energy is greater than that of the surrounding air.

 

[spareine]

Why don't we get an electric shock when we touch it?

You do not get an electric shock because the current is limited by the internal resistance of the voltage source.
If there is a small air gap between the globe and your hand, a discharge may develop in that gap, perceived by a hissing noise and the odor of ozone. If you put a piece of aluminium foil on the globe, your finger may receive a small shock.