Re: Zero with units?

[James Frysinger <frysingerj@COFC.EDU>]

On Monday 20 September 2004 03:19, brian mcinnes wrote:
> on 20/9/04 5:34 AM, James Frysinger at frysingerj@COFC.EDU wrote:
>
> SNIP
>
> > "the potential at this point is 0 V".
>
> SNIP
>
> James, would you (or any other contributor) care to comment on the
> following.
>
> When I read 3V, I interpret that as a value greater than 2.5V and less than
> 3.5V.  If what was meant was 3.0V, then it should have been written as 3.0V
> (and then I would interpret it as greater than 2.95V and less than 3.05V).
>
> So, when I read 0V, is that really zero, or is it a value somewhere between
> 0.0V and 0.5V?
>
> Brian McInnes

        Typically, at least in IEEE standards, 3 V implies a likely range of 2.5 V to
3.5 V. As do most physicists, we use significant figures to imply the
uncertainty. Of course, an explicit statement of the uncertainty is more
elegant and less ambiguous.

        If I were to measure the potential at some point in a circuit (with respect
to chassis ground, for example) and stated that it was 0 V, I would probably
mean that to imply that the potential falls between -0.5 V and +0.5 V.

Jim

--
James R. Frysinger
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