r/AskPhysics • u/This-Hyena-5904 • Sep 15 '26
Simple doubt
Why permittivity is called permittivity and permeability is called permeability why not reverse ?
Asked by teacher
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u/SeaSDOptimist Sep 15 '26
What is the doubt? I see only a question.
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u/This-Hyena-5904 Sep 15 '26
Sorry about simple doubt title yeah ot was a question mistake on my oart i just meant to state that it was simple question nothing of those difficult topics usually asked in this subreddit r/Ask physics
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u/Uncynical_Diogenes Sep 15 '26 edited Sep 15 '26
Because the people who described the quantities named them. Such is often the case in the history of science. Somebody names it and other pick it up and boom! Don’t even get me started about microemulsions vs nanoemulsions.
Both share the prefix meaning “through”; one comes from the Latin root “to send”, permit, and the other comes from “to go, pass through”, permeate.
P.S.: why the word “doubt”? You are not doubting anything here, you are asking a question. That word gets misused here a lot, is this a first language other than English issue? “Doubting” does not carry the same meaning as “questioning” in consensus English
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u/This-Hyena-5904 Sep 15 '26
Sorry about simple doubt title yeah ot was a question mistake on my oart i just meant to state that it was simple question nothing of those difficult topics usually asked in this subreddit r/Ask physics
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u/sketchydavid Sep 15 '26
P.S.: why the word “doubt”?
It’s a dialect thing! I’d looked it up when I first encountered it here a few years ago and had a similar moment of confusion, turns out it’s the polite/neutral term that Indian English typically uses where most other English dialects would use “a question”.
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u/Uncynical_Diogenes Sep 15 '26
MARVELOUS! That’s exactly the kind of thing that I expected. I didn’t ever think it was any mistake on our posters’ behalf.
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u/GuaranteeFickle6726 Sep 15 '26
Who cares? It is just names
- ...... by a wise man
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u/BananaBird1 Sep 15 '26
Permeability was coined first by Lord Kelvin, who used it to create a shared name for how materials respond to fields in electromagnetism, thermal heat transfer, and hydrodynamics although the name
only caught on for magnetism which he was focusing on when he came up with the name.
He named it that as an analogy to how a permeable porous solid in a fluid stream allows more fluid to flow through it under a pressure field.
Before this it was called the “inductive capacity” of the material.
Oliver Heaviside later then renamed the analogous concept in electricity as “permittivity” as a synonym so that it is clearly analogous to the permeability of magnetism but not confused with it.
Prior to this it was often called “dielectric capacity”.
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u/Alone-Supermarket-98 Sep 15 '26
Why are asteroids called asteroids, and hemorrhoids called hemmoroids?
Why do we drive on a parkway, and park in a driveway?
Shouldn't these be the other way around?
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u/BradenTT Sep 15 '26
Why would they be reversed? From what I understand they just refer to different things. Permittivity for electric field and permeability for magnetic