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I'm from Czech Republic, born 1980. From elementary school, we all remember this mantra:

When ebonite rod is rubbed with fox fur, electrostatic charge is created. Electrostatic charge is created by rubbing ebonite rod with fox fur. Rubbing ebonite fur with fox fur creates electrostatic charge.

Etc. ad nauseam.

So...

Is there anything special about the combination of ebonite and fox fur that makes it especially useful for teaching kids about electricity?

Does there even exist a clear distinction between things that do and things that don't create electrostatic charge by rubbing?

The irony: I can't remember ever hearing the word 'ebonite' in any other context than this particular strange example. (I never even knew what ebonite was until about 15 minutes ago when I googled it.)

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    $\begingroup$ Fur and amber is the traditional version, but amber is not cheap. $\endgroup$
    – Buzz ♦
    Commented Jan 12, 2019 at 6:26
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    $\begingroup$ Ebonit and fur are particularly good for experimental demonstrations. Note that it works with fur alone: beating repeatedly a russian hat against someone's back and then touching them is bound to create a noticeable discharge - I checked it many times as a schoolkid ;) $\endgroup$
    – Roger V.
    Commented Oct 21, 2021 at 8:40

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You're looking for the triboelectric effect.

The triboelectric series is an empirical table of materials in order, such that materials high on the list tend to give electrons to materials lower on the list. Fur is high, ebonite is low. Materials of similar index don't build up much charge separation from rubbing, while materials with largely different index do.

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The electrons in fur are much less tightly bound than electrons in ebonite (very strong relative bond, ebonite is at the bottom of the negative Triboelectric series, see [1]) and hence ebonite gets a strong relative negative charge [1].

"A material towards the bottom of the Triboelectric series table, when touched to a material near the top of the series, will acquire a more negative charge."

So to answer the question, this particular combination of materials will cause a very strong electrostatic effect. Ebonite is very strong negatively static charged.

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Static electricity is observed with a plastic comb after you comb dry hair. So there is nothing special about ebonite except ancient report which led to the name electricity.

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  • $\begingroup$ I think you are confusing ebonite with amber (named electrum in Latin, from elektron in Greek). Ebonite is hardly ancient, it was invented by Goodyear in 1839. $\endgroup$
    – PM 2Ring
    Commented Jan 12, 2019 at 12:45
  • $\begingroup$ You are absolutely right. I did make that mistake about the name. But the physics argument stands. There is nothing special about ebonite or fir that matter amber $\endgroup$
    – Dr S T Lakshmikumar
    Commented Jan 12, 2019 at 15:22

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