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Re: Capacitor Charged, Right term



On Fri, 13 Feb 1998, LUDWIK KOWALSKI wrote:

To stop saying "a capacitor is charged" is like stop using the noun "heat".
It is too late; an individual teacher has no control over what textbook
writers and other teachers say. What I would do, as the result of this
exchange of ideas
Oop, I ment to say what I WILL start doing is to emphasize that the net
charge is always zero because ..., etc. I was not aware how the common
phrase can be interpreted.

Not being a teacher, I haven't experimented with various solutions. If
there was TIME, I think that presenting to students the "charge"
controversy (and also the "heat" controversy) would be very helpful.
Just reading phys-L messages is far better than most textbooks I've
encountered.

However, note that our use of "heat" and "charged" are traditions.
Traditions are "memes" or mental viruses. They travel by infection and
proceed like epidemics. They can be fought with "innoculation". If
enough people begin to feel funny about using the terms "heat" or
"charged", they will warn others about it. The innoculated population
will proceed through an exponential growth era. I could hope.

In my own head, I often say "electrify a capacitor", meaning "store
e-field energy within". Or sometimes I say "separate the charge of a
capacitor" which helps me remember that metals are already full of charge.
I've come to imagine the innards of a capacitor as being like a rubber
band, and I can stretch the rubber but never can create any rubber. Or,
it's like a motor/pump which is connected to a spring-powered motor. If I
force charge through it, the spring winds up, and if I stop forcing it and
instead provide a path between its terminals, the spring unwinds and
drives the pump to cause charge to flow. But no charge is stored and/or
released.


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