Nuts and Bolts: the coulomb.

The SI System - the Système Internationale of measurement, used, as its name suggests, throughout the world - has been designed to be easy. No fourteen-pounds-to-a-stone, but a thousand grams to a kilogram; no 1,760-yards-to-a-mile, but a thousand metres to a kilometre; and a litre of water has a mass of 1 kilogram, pretty much, whereas a pint of water weighs a pound and a quarter.


Except...

A coulomb is the SI unit of electrical charge. It is the charge transported by a constant current of one ampere in one second.

Unfortunately this means that a faraday (the unit of charge of one mole of electrons) has a value of about 96,487 coulombs, and in terms of the Avogadro constant (you can find an entry about it on Wikipedia if you're interested) one coulomb equals approximately 1.036 x 10 to the minus five mol x NA elementary charges.

Now, as far as I understand it, this is partly caused by Nature being jolly awkward; but I do wonder if the SI system really should have embraced a method of measurement where a second is an 86,400th of a day.

Mind you, the idea of a day is pretty whoozy and non-scientific, isn't it?

Word To Use Today: coulomb. The coulomb is named after the French scientist Charles-Augustin de Coulomb.