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Electric currents (the rate at which charges pass 
a fixed point in a wire, for instance) have dimensions of 
charge per unit time.  
If the  COULOMB is our chosen unit for electric charge 
and we retain our fondness for seconds as a time unit, 
then current must be measured in coulombs per second.  
We call these units  AMPERES or Amps [abbreviated A] after 
a Frenchman named Ampère.  Thus 
| ![\begin{displaymath}1 \, \hbox{\rm A [{\sc ampere}]} \; \equiv \; 1 \, \hbox{C/s
[{\sc coulomb} per second]}
\end{displaymath}](img76.gif) | (17.18) | 
 
I have a problem with Amps.  
It makes about as much sense to give the coulomb per second 
its own name as it would to make up a name for meters per second.  
No one frets over the complexity of expressing speed in m/s 
or kph or whatever - in fact it serves as a good reminder 
that velocity is a rate of change of distance with time - 
but for some reason we feel obliged to give C/s their own name.  
Ah well, it is probably because all this electrical stuff is 
so weird.17.12
Whatever the reason, we are stuck with them now!  
 
 
 
 
 
   
 Next: The Coupling Constant
 Up: Electrical Units
 Previous: Electron Volts
Jess H. Brewer 
1999-01-12