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Next: The Coupling Constant Up: Electrical Units Previous: Electron Volts

Amperes

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} (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 up previous
Next: The Coupling Constant Up: Electrical Units Previous: Electron Volts
Jess H. Brewer - Last modified: Mon Nov 16 17:16:21 PST 2015