Re: New capacitor problem

[inet@intellisys.net (brian whatcott)]

At 11:16 AM 3/29/97, Donald E. Simanek wrote:
> On Sat, 29 Mar 1997, brian whatcott wrote:
>
> > It is  quite declasse, I'm sure, to offer water analogies in the didactic 
> > environment for teaching physics or electronics.
> >
> >  But try this:
> >
> > 1) A bucket is charged with 8 pounds of water, and the height of
> > the water level is found to be half way up the bucket.
> >  What is its water capacity?
> >
> > 2) The bucket is now emptied.
> > What is its water capacity now?
>
> Most here know me as a critic of all analogies except the mathematical
> analogy.

I suspected as much. You are not alone. There is a hunger for exactitude.
 But there once was a person foolish enough to run with the analogy of a
table-tennis session aboard a train or some such foolishness.

  Then again, he was only a clerk, second class ( I heard he started as a 
clerk third class, would you believe.)

    Moreover, the only Nobel he ever received was for some work involving a 
polished piece of copper plate and a uv lamp as I recall.

> > If people can answer the water problem but not the capacitor question,
> > it seems to me their teaching has been impoverished by the absense of 
> > helpful analogy.
>
> It seems to me that analogies such as this one impoverish students'
> conceptual understanding, and lead to incorrect conclusions.
It's not MY students that conclude that a discharged condenser has no 
capacity for charge!   :-)

> >   (Just wait 'til I get going on the helpful role that silly mnemonics
> > play on students' competence....)
> >
> > :-)
> >
> > brian whatcott
>
> This is the kind of useful and provocative give-and-take I was hoping to
> inspire by posting this problem.  
>
> 	-- Donald
.....and it is quite unfair of me to start throwing shells down from the 
peanut gallery, as a newcomer to this enterprise.

Regards
brian whatcott <inet@intellisys.net>
Altus OK