OT: Speed of light

Erik Max Francis max at alcyone.com
Thu Feb 14 06:07:14 CET 2008


Bjoern Schliessmann wrote:

> eV has a advantages some "kilogram force" hasn't: It's on completely
> different order of magnitude. People aren't happy writing 81.8 aJ
> (Attojoule = 1e-15 Joule), instead they prefer 
> 511 keV.

A couple of problems here.  1 eV = 1.602 x 10^-19 J.  Also, the atto- 
prefix is 10^-18, not 10^-15.  So 511 keV = 81.9 fJ (femtojoules).  (All 
values to three significant figures.)

If you want to deal with a unit on the order of the size of the 
electron-volt, then you have to one rung down from even atto-, which is 
(wait for it) zepto-.  The electron-volt is about 160 zJ (zeptojoules).

-- 
Erik Max Francis && max at alcyone.com && http://www.alcyone.com/max/
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