Static Charge & Humidity: A Closer Look

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Discussion Overview

The discussion revolves around the phenomenon of static charge accumulation in relation to humidity levels in the air. Participants explore the reasons why static charge builds up more readily in dry conditions compared to humid ones, examining concepts such as the conductivity of water, the role of water dipoles, and the effects of water vapor on charge transfer.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that static charge builds up more easily in dry air because water molecules coat surfaces under humid conditions, potentially affecting charge accumulation.
  • Another participant argues that ordinary impure water is a decent conductor of electricity, which allows charge to leak off more readily in humid conditions.
  • A follow-up question raises the role of water dipoles in charge conduction and whether pure water would behave differently.
  • One participant clarifies that water vapor in the atmosphere is pure and questions the conductivity of water vapor compared to liquid water.
  • Another participant proposes that water condensing on insulators increases their conductivity, making it harder to build up or transfer charge.
  • A different viewpoint suggests that the dipole nature of water can capture loose electrons, thereby reducing static charge accumulation.

Areas of Agreement / Disagreement

Participants express differing views on the role of water's conductivity and dipole nature in static charge accumulation, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Participants discuss the implications of water purity and the state of water (vapor vs. liquid) on conductivity, but the discussion does not resolve the complexities of these factors or their interactions.

Who May Find This Useful

Individuals interested in electrostatics, the effects of humidity on charge accumulation, and the properties of water in electrical contexts may find this discussion relevant.

cepheid
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Why does static charge build up more easily in dry air? One site on the WWW mentioned that it has to do with the fact that under humid conditions, water molecules coat surfaces. I know that water molecules have net dipoles, but it's not really clear what effect that has.
 
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The primary reason is that ordinary impure water is decent conductor of electricity. So the charge keeps leaking off and doesn't build up as well as on a dry day.
 
Thanks! That makes sense. So, what about the dipoles? Do they factor in at all? Or would their be no conduction if (hypothetically) the water were pure?
 
Doc Al said:
The primary reason is that ordinary impure water is decent conductor of electricity. So the charge keeps leaking off and doesn't build up as well as on a dry day.

But water vapor in the atmosphere isn't "impure" like liquid water is from the ions disolved in it. The water vapor is pure water since you can't evaporate ions that were once in the liquid water. So, if what I say is true, then the reason why static charge builds up better in dry air is because the water vapor in the moist air is a bad conductor.
 
ArmoSkater87 said:
But water vapor in the atmosphere isn't "impure" like liquid water is from the ions disolved in it. The water vapor is pure water since you can't evaporate ions that were once in the liquid water.
You make a good point, Armo. On further thought, a better answer is that the water that condenses on the surfaces of the insulators makes those surfaces more conductive. Thus it's harder to build up or transfer a charge.
So, if what I say is true, then the reason why static charge builds up better in dry air is because the water vapor in the moist air is a bad conductor.
That doesn't make sense. You want the air to be a bad conductor to build up a static charge.
 
Can't the + side of a water dipole simply grab any loose electron, thereby eliminating any static? I think water just grabs the extra electrons as it would grab +ions.

With no dipole around, the electrons are free to build up and charge things, and shock us.

Basically, when its humid, the humidity gets electrically shocked, instead of us.
 

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