Useless fact I just learned from Wikipedia: Ångström/Angstrom (in Sweden of course we still use the original spelling) has its own UNICODE symbol, Angstrom sign: Å (U+212B) not to confuse with the Swedish letter Å (U+00C5). Looks slightly different in my browser.
replyLooks like that's deprecated. From the next sentence:
replyHowever, version 5 of the standard already deprecates that code point and has it normalized into the code for the Swedish letter U+00C5 Å `latin capital letter a with ring above`
Aaahhh, ok, thanks!
replyYou had the right idea. Angstroms are not an SI unit. The SI units jump by three orders of magnitude at this scale: picometer, nanometer, micrometer, millimeter.
reply(In the same way that meter jumps three orders of magnitude to kilometer[1], or millions to billions to trillions, etc.)
[1] Technically there are intermediate SI units between meter and km but nobody uses them. There are not intermediate SI units between the tiny ones.
Why above 1mm do we go by tens instead of thousands?
replyWe have centimeter (10 mm) then decimeter (100mm) then meter (1000mm). Then we jump to thousand again (kilometer).
>We have centimeter (10 mm) then decimeter (100mm)
replyDoes anyone actually use those? I think I would throw up a little in my mouth if I saw either of those on a mechanical drawing.
Answer that question and you'll get the whole impetus for logarithmic scales.
replyEveryday necessity. The gap between mm and m is too large, there are many things in daily life that are better expressed in cm. SI units must strike a balance between three factors: not having so many denominations nobody can remember them; not having so few denominations that using them adds too much wordiness to daily life (150mm or 0.15m are wordier than 15cm); and a degree of familiarity with the everyday units people used before metric, to smooth the transition and encourage adoption.
reply