Re: Unit Scaling Prefixes: (was Birthday Wish)

[paul o johnson <pojhome@FLASH.NET>]

It's even worse when you make such prefix mistakes yourself. While preparing
exams on my computer, I have more than once forgotten to change Times Roman to
Symbol in prefixes and units and thus given my students a problem containing
milliFarads instead of microFarads or, even worse, milliwatts instead of
micro-ohms.

Why doesn't someone invent a scientific keyboard having separate keys for the
more common Greek letters?

poj

brian whatcott wrote:

> Although I deny that engineers use M for milli- or micro-, I acknowledge
>  that electronic components are often mismarked in this way.
> So there is virtue in Douglas's warning. In these cases, context can
> provide guidance. But these days, capacitors can take values between
> picofarads to farads and all points between. So the old rule of thumb about
> a mismarked
> "mF" or "MF"  more likely meaning microfarad (uF) than millifarad (mF) has
> lost its strength. But because there is no instance of a megafarad capacitor
>  ever (yet), one can at least discard that possibility.
>
>   But in measuring frequency, I have seen reference to measurements in
> millihertz just once, while megahertz tags are legion.
> There was a reference in the splendid French-U.S work on resolving
> breathing mode frequencies of the Sun, that I have mentioned before.
>  They used the Fourier transform of an unbroken train of solar observations
> of the Doppler shift of some hyperfine Sodium line taken in, I think, the
> Antarctic.
>
>  So as a sweeping generalization, I'd say measurements in millihertz are
> to be found rarely among physicists, and not often from engineers, where
> the context is generally informative.
>
> Brian
> brian whatcott <inet@intellisys.net>
> Altus OK