# Why eletric charge in Dimensional Analysis and not eletric current?

1. Sep 14, 2011

### ksio.amaral89

2 questions,actually:

1-Why in Dymensional Analysis is eletric charge a basic physical dimension instead of eletric current(as Ampere is a SI base unit and Coulomb isn't)?

2-I've read CIPM(or International Committee for Weights and Measures in English) is proposing new definitions for some of the current 7 base units,in which the supporters want to set some of the current definitons based on fundamental constants such as Avogadro or Planck constants.For further information:

http://www.bipm.org/cc/CIPM/Allowed/98/CIPM2009_49_TIMING_THE_NEW_SI.pdf

What's your opinion?Do you consider that the current SI definitions need revisions?

Last edited: Sep 14, 2011
2. Sep 15, 2011

### Blibbler

As you know, current is the rate of flow of charge and therefore the unit of charge is simpler than the unit of current. Relativity has a lot to do with charge being a more convenient unit than current as charge is not affected by time dilation so the Coulomb remains the Coulomb whereas the Ampere depends on your frame of reference.