Friction on a Rainy Day: Why Does a Comb Stop Attracting Paper in Wet Hair?

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SUMMARY

The discussion centers on the phenomenon of a comb attracting bits of paper when used on dry hair versus wet hair. It is established that wet hair reduces friction between the comb and hair, which diminishes the comb's ability to generate static electricity. Additionally, the presence of water molecules in humid conditions leads to charge dissipation, preventing the buildup of static that is necessary for attraction. The hygroscopic nature of hair also contributes to changes in surface texture, further affecting friction and charge accumulation.

PREREQUISITES
  • Understanding of static electricity and charge polarization
  • Basic knowledge of molecular interactions and friction
  • Familiarity with hygroscopic materials and their properties
  • Concept of surface roughness at the molecular level
NEXT STEPS
  • Research the principles of static electricity and charge buildup
  • Explore the effects of humidity on material properties and friction
  • Study the molecular structure of hair and its hygroscopic behavior
  • Investigate the role of water molecules in charge dissipation
USEFUL FOR

This discussion is beneficial for physicists, materials scientists, and anyone interested in the interactions between static electricity and environmental conditions, particularly in relation to everyday materials like hair and combs.

phymathlover
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A comb run through dry hair attracts bits of paper. What happens if your hair is wet or it is a rainy day?
I guessed that the comb would stop attracting paper, what bothers me is why. My book says its because if my hair is wet or its a rainy day, the friction between the comb and my hair reduces. I don't understand how exactly that happens. I mean wouldn't the comb still be up against the same amount of roughness on the molecular level.
Also, I thought the reason could be because when it is wet, there are more H2O molecules around so they get polarised and act as preventive forces in the space between the comb and the paper and thereby prevent the paper from being polarised and hence be attracted towards the comb.
Does that make any sense? I confused myself while writing this XD
 
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I think hair is hygroscopic, absorbing moisture on humid days then losing some when humidity drops. So the fibres probably swell slightly and become smoother, so maybe friction really is different in damp weather. But I think the main problem is that charges quickly leak away over damp surfaces in humid weather so it doesn't have a chance to build up to the 'crackling' stage.
 

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