Why Does a Razor Blade Move Away from a Charged Body on Water?

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Discussion Overview

The discussion revolves around the phenomenon of a razor blade moving away from a charged body when placed on the surface of water. Participants explore potential explanations for this behavior, considering both theoretical and experimental perspectives.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the phenomenon, asking for references to support the claim that a razor blade moves away from a charged body.
  • Another participant suggests that the movement could be due to eddy currents.
  • A different participant provides a detailed explanation involving induced surface charge on the razor blade and the resulting electric field, proposing that this could affect the water molecules and lead to the blade moving away.
  • Some participants express skepticism and request credible sources to substantiate the claims being made, indicating a desire for more reliable information.

Areas of Agreement / Disagreement

There is no consensus among participants regarding the explanation for the razor blade's movement. Multiple competing views and hypotheses are presented, and the discussion remains unresolved.

Contextual Notes

Participants note the lack of credible sources to support the claims, which may limit the depth of the discussion. The assumptions underlying the proposed explanations are not fully explored.

ellinas
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why does a razor blade placed on the water surface move away from a charged body?
 
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I didn't know it did. Can you give us a pointer to a reference that discusses this experiment?
 
could be due to eddy currents
 
Never heard of it. But..

A charged body near a conductor will induce a surface charge, distributed so that there is zero electric field within it (this is similar to dielectrics, and should very weakly attract the conductor, in the absence of other effects). Such a distribution always has to be concentrated at any points or edges (compared to flat surfaces), and so the highest charge density (and strongest electric field) should occur along the razor blade. This most likely transfers charge to water molecules there, or at least raises the water pressure near the blade (dielectric fluid prefers being near high charge density), floating the razor blade in the opposite direction, but that's a bit of a guess.
 
guys hasn't any idea on this?
 
ellinas said:
guys hasn't any idea on this?

As I said, it would help a lot if you could list a credible source for this claim, so that we can go read about it and help to explain it to you. Without a credible source for us to look at, it is unlikely you will get much more than wild guesses.
 

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