really silly nit: why 3+5j instead of 3+5i?

andres at andres at
Sun May 14 13:07:28 CEST 2000

On Sat, May 13, 2000 at 10:41:01PM -0600, Andrew Dalke wrote:
> Just scanned through one of my E&M books.  Can't find "i" used for
> current.  Found "I", and dQ/dt.  Also found J used for volumn current
> density.  Lower case "i" is used for imaginary numbers and i^ (that's
> i-with-caret) for unit vector along the x axis.
> Can't ever recall using "i" for current.
>                     Andrew
>                     dalke at

You are correct that "I" is the soft standard for current in physics
textbooks but no one would misunderstand you if you used "i" also. It's also
very common to see "q" for charge instead of "Q". An online example of the
use of "i" for current can be seen at:

which describes Maxwell's equations (the fundamental laws of

My point still stands: being worried about confusing "i" between current or
an imaginary number is something that only engineers mention, the rest of
the scientific world aligns itself with the mathematical world (presumably
the more "authoritative" source of "proper" notation).

Andres Corrada-Emmanuel Email: andres at

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