Plasma ball electric shock mystery

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SUMMARY

The discussion centers on the phenomenon of why touching a plasma ball does not result in an electric shock despite its high voltage. The primary reason is that the glass of the plasma ball acts as an insulator, preventing direct current flow. When a finger touches the glass, it creates a conductive path due to the body's parasitic capacitance, allowing radio frequency (RF) energy to flow. The internal resistance of the voltage source limits the current, ensuring safety. A small shock may occur if an air gap exists or if conductive materials like aluminum foil are introduced.

PREREQUISITES
  • Understanding of high voltage concepts
  • Knowledge of electrical insulation properties
  • Familiarity with radio frequency (RF) energy
  • Basic principles of capacitance and resistance
NEXT STEPS
  • Research the properties of insulators and conductors in electrical systems
  • Learn about parasitic capacitance and its effects in electrical circuits
  • Study the behavior of radio frequency energy in different materials
  • Explore safety measures when working with high voltage equipment
USEFUL FOR

This discussion is beneficial for electrical engineers, physics students, and hobbyists interested in understanding the principles of high voltage phenomena and safety precautions related to plasma devices.

Herbert Cheung
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Plasma ball has a high voltage. Why don't we get an electric shock when we touch it?
 
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Herbert Cheung said:
Plasma ball has a high voltage. Why don't we get an electric shock when we touch it?
Glass is an insulator. :smile:
 
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Oic @berkeman
So why is the plasma thread attracted to my hand when we touch it?
 
Herbert Cheung said:
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? :smile:
 
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It's actually a very interesting question. The answer seems to be that your finger gets RF energy.

https://en.wikipedia.org/wiki/Plasma_globe said:
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.
 
Herbert Cheung said:
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.

plasmaball.png
 

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