Rubber soled slippers generating static electricity

[berkeman]

so I will try out those shoe covers because I don't want to accidentally spark a fire

Unless your work/live in an environment with lots of natural gas concentrated in the air (and you would smell the strong odor of Mercaptan) , the risk of starting a fire or explosion with a static shock is pretty much non-existent.

 

[MaryYamada]

I don't have that natural gas issue you mention, unless you factor in our gas stove, dryer and gas fireplace, but those shocks are pretty painful...so, if only for my own pain-free peace of mind and body.....

 

[Tom.G]

(prompted by a PM w/@MaryYamada)

For carpets generating static charges, see post #10
https://www.physicsforums.com/posts/6127376/

Cheers,
Tom

 

[spareine]

A mechanism that's often neglected is Electrostatic Induction and I think it is a more common way that things can become charged than simple 'charge sharing'

I agree it is a good exercise to compare the person to an electrophorus, and to consider the possibility of touching ground while seated, theoretically. However, I am not sure why you refrained from estimating the magnitude of your effect of touching ground while seated. See the figure. Suppose the penetration depth of the triboelectric charge is ~1 μm if the person is sitting, then the charge separation distance in C1 is ~1 μm, or less. In contrast, the separation distance in C2 is 1 cm or more. So merely ~0,01% of the charge of C1, or less, would be transferred to C2.
In practice, it is easy to verify that touching ground while seated hardly affects the excursion of the electroscope after rising from the chair, or the propensity to spark.

 

[sophiecentaur]

So merely ~0,01% of the charge of C1, or less, would be transferred to C2.

I was thinking about it differently. I assumed that the charge separation between chair and seat would be due to friction between seat and trousers. (Why do you estimate 10mm between body and seat? Clothing (compressed) would only be a mm or less.) Displaced charge on the body would travel to the car body through the wheel and controls. The charge separation process would be gradual as the driver fidgets in her seat so no shock experienced when touching the wheel. You operate the door lock before you move off the seat so no shock. You then slide out, which produces a high PD (Q=CV) and C reduces a lot due to separation. You then turn round and touch the door and that's when you get the shock.
Iirc, I have experimented with holding the door whilst actually stepping down onto the ground and that reduced / eliminated the shock.
Second thoughts - perhaps the car body charges up when moving through dry air and the driver, inside the shell, has no charge. Stepping out of the car, the uncharged driver can then touch the charged car body but that would rely on some nifty movement to avoid touching the door handle until the driver is definitely outside it.

 

[spareine]

I was thinking about it differently. I assumed that the charge separation between chair and seat would be due to friction between seat and trousers. (Why do you estimate 10mm between body and seat? Clothing (compressed) would only be a mm or less.)

Then my diagram was not clear enough. The capacitors C1 and C2 together are a stack of three electrically charged layers: (A) the lower surface of the body, including the trousers, negatively charged due to the triboelectric effect; (B) upper surface of the seat cushion, positively charged due to the triboelectric effect; (C) the chair frame that supports the cushion, connected to Earth or the car body. C1 is the capacitor AB; C2 is capacitor BC. The distance between the charges of A and B is very small. The distance between B and C is the thickness of the cushion, at least 1 cm.

Iirc, I have experimented with holding the door whilst actually stepping down onto the ground and that reduced / eliminated the shock.

I thought you implied in post #48 that the final spark when leaving the car could be reduced in an earlier stage by touching the frame while driving. But now I understand you are saying that the final spark can only be reduced by touching the frame while rising from the chair. I agree with that (as in post #12).

 

[sophiecentaur]

I thought you implied in post #48 that the final spark when leaving the car could be reduced in an earlier stage by touching the frame while driving. But now I understand you are saying that the final spark can only be reduced by touching the frame while rising from the chair. I agree with that (as in post #12).

Living in UK, I don't have a lot of problems with this but I do find it quite difficult to exit a car without losing contact with it at some stage. We agree that's the critical stage. There must be a way of attaching a wire before exiting but that would be a fiddly process and I know I'd forget to do it on the driest day of the year!

The distance between B and C is the thickness of the cushion, at least 1 cm.

Right - I get your model now. However, I would suggest that the charge separation would occur whilst sliding / exiting and the charges would be right on the surface of the seat.

But if it were as simple as our discussion suggests, wouldn't seat manufacturers use appropriate seat fabric?

 

[spareine]

Right - I get your model now. However, I would suggest that the charge separation would occur whilst sliding / exiting and the charges would be right on the surface of the seat.

Agreed

But if it were as simple as our discussion suggests, wouldn't seat manufacturers use appropriate seat fabric?

Maybe the manufacturers found out that antistatic seats were low on the priority list of buyers

 

[sophiecentaur]

AgreedMaybe the manufacturers found out that antistatic seats were low on the priority list of buyers

A shocking price to pay?

 

[auzo63]

I have the same problem and it hurts like hell. But I have NO carpets in my home only ceramic tiles.

 

[C4m]

Went into a similar issue. Always when wearing Polyester trousers and getting up after sitting/laying on a wooden, cotton coated bed. Then slippng into some rubber slippers and always getting zapped at the next Sink/PC/Buddy... Literally anything that is differently charged.

Personal Workaround so far...
-Take off/ exchange those trousers.
-Walk barefoot, or touch the ground (barefoot for better results) before slipping into those slippers.

Optimal solution:
Calculate and construct a antistatic wrist/ankle Band with adjustable length that will fit your local living room..