5 ms·
What I don't get is why ampere is a fundamental unit while coulomb isn't. I mean, it seems more natural to think of amperes and coulombs per second rather than
by quanticle 15y ago
What I don't get is why ampere is a fundamental unit while coulomb isn't. I mean, it seems more natural to think of amperes and coulombs per second rather than to define coulombs as the amount of charged carried by a 1 amp current in 1 second.
- jessriedel 15y agoTechinically, neither the Coulomb nor the Ampere are fundmental. Both are derived from the meter, second, and kilogram. http://en.wikipedia.org/wiki/File:SI_base_unit.svg http://en.wikipedia.org/wiki/File:SI_base_unit.svg Now, in the abstract, yours is the more natural definition. But experimentally, it turns out to not give the best accuracy. I believe one starts with (1) the meter (which is based on a second defined using a atomic transition, plus light) and (2) the Newton (which is the force required to accelerate the all-important kilogram at 1 meter per second squared). Then an Ampere is the amount of current flowing through two parallel wires required to produce a force of one Newton per meter between the wires. http://en.wikipedia.org/wiki/Ampere#Definition http://en.wikipedia.org/wiki/Ampere#Definition Now, the technology is apparently improving enough that it may be possible to actually count elementary charges like you suggest. See here: http://en.wikipedia.org/wiki/Ampere#Proposed_future_definition http://en.wikipedia.org/wiki/Ampere#Proposed_future_definiti...