Re: Electric Potential

[Hugh Haskell <hhaskell@MINDSPRING.COM>]

At 11:42 -0600 2/6/02, Tina Fanetti wrote:
> The question is from Peer Instruction by Mazur.  It is on page 233, #5.
>
> This is the question
> "If the electric field E equals zero at a given point, must the
> potential difference V also equal zero at that point?  Give an
> example to prove your answer."
>
> That is the exact question.
Then I am afraid that Mazur has written a very poorly-worded
question. As JD has pointed out, a potential difference can only
exist *between* two points, not *at* a single point.

If a zero of potential had been established at some previously
designated point, then the question could be asked, "must the
potential V [relative to the previously designated zero point] also
equal zero at that point?"

Since the location of the point at which the potential can be defined
to be zero is arbitrary, it is clear that there is no requirement for
the potential relative to that arbitrary point must be zero just
because the field happens to be.

Hugh
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Hugh Haskell
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