Re: [Phys-L] voltage rise/drop terminology

[John Denker <jsd@av8n.com>]

On 04/09/2014 10:21 AM, Bernard Cleyet wrote:

> >  students develop a good understanding of current flow in 
> > simple circuits. [1]

> isn’t flow or current redundant?

I think BC has a point.  Actually it's worse than redundant.
Mere duplication would be harmless, but "current flow" is
actually bad physics.  Current is a vector, with direction
and magnitude.  Actual flow of current would be a second-
rank tensor.  Such things do exist in physics;  in particular
a shear force is equivalent to a flow of momentum, which is
a second-rank tensor.

There's a simple way to fix statement [1] so that everybody
is happy:  

--> students develop a good understanding of current 
     as it flows in simple circuits.      [2]

Current is a flow.  The flow flows in simple circuits.
That's duplicative but harmless.

I recommend staying away from flow "of" current, and away
from "current flow".  One could argue about what "current
flow" means, but AFAICT it's not worth the trouble,
given that [2] solves the problem with no arguing required.

> How about electrical energy flow, of just plain current.  

Just plain current is fine.

However, just plain current is not equivalent to energy
flow.  Not even close.  Current is the flow of electrical
/charge/.

Charge is conserved, and energy is conserved, but these
are two different, independent conservation laws.