Electrical current is a 4-vector, is it not?
> Correct! - and an alternating electric current is represented as a > complex number (then it's conventional to use the symbol 'j' for > sqrt(-1) to avoid confusion with 'i', the symbol for electric > current!). Since as you say electric current is a scalar not a > vector, then a complex number has to be a scalar, not a vector! > > Cheers > > -- Ian > > On Thu, Oct 14, 2010 at 3:47 PM, Ganesh Natrajan <natra...@embl.fr> wrote: >> The definition of a vector as being something that has 'magnitude' and >> 'direction' is actually incorrect. If that were to be the case, a >> quantity like electric current would be a vector and not a scalar. >> Electric current is a scalar. >> >> A vector is something that transforms like the coordinate system, while >> a scalar does not. In other words, if you were to transform the >> coordinate system by a certain operator, a vector quantity in the old >> coordinate system can be transformed into the new one by using exactly >> the same operator. This is the correct definition of a vector. >> >> G. >> >> >> >> On Thu, 14 Oct 2010 10:22:59 -0400, Ed Pozharski >> <epozh...@umaryland.edu> wrote: >>> The definition game is on! :) >>> >>> Vectors are supposed to have direction and amplitude, unlike scalars. >>> Curiously, one can take a position that real numbers are vectors too, >>> if >>> you consider negative and positive numbers having opposite directions >>> (and thus subtraction is simply a case of addition of a negative >>> number). And of course, both scalars and vectors are simply tensors, >>> of >>> zeroth and first order :) >>> >>> Guess my point is that definitions are a matter of choice in math and >>> if >>> vector is defined as an array which must obey addition and scaling >>> rules >>> (but there is no fixed multiplication rule - regular 3D vectors have >>> more than one possible product), then complex numbers are vectors. In >>> a >>> narrow sense of a real space vectors (the arrow thingy) they are not. >>> Thus, complex number is a Vector, but not the vector (futile attempt at >>> using articles by someone organically suffering from article dyslexia). >>> >>> Cheers, >>> >>> Ed. >>> >>> >>> O >> -- >> ********************************************** >> Blow, blow, thou winter wind >> Thou art not so unkind >> As man's ingratitude; >> Thy tooth is not so keen, >> Because thou art not seen, >> Although thy breath be rude. >> >> -William Shakespeare >> ********************************************** >> >
