Re: Conserving Q ?

[Bob Sciamanda <trebor@VELOCITY.NET>]

Ludwik wrote:
. . .
> An experiment was performed showing that I1 is largerthan I2.
> And integrals of currents (when I1>0 and I2>0) differ in the same
> way. For example, I1=5*I2 and Q1=5*Q2. Would such data be in
> conflict with the law of conservation of electric charges? . . .


The conservation of Q thesis is vindicated if you can find the "missing"
charge elsewhere!

. . .
> Some say the displacement current is a mathematical
> abstraction (extremely useful); it is not a real current. What
> makes it less real than other abstractions, such as "ohmic
> current" in a wire, or "water current" in a tube?
> Ludwik Kowalski

To me the displacement current is a USEFUL* concept, on a par with
"charge" current because both are equally curl sources of the magnetic
field.  Mathematically, both contribute to

Curl (B) = mu *( j  + dD/dt ).

Note that without the second term on the RHS, Stoke's law can be made to
fail (at best becomes schizophrenic) when applied to this equation -
(that is mathematically why Maxwell added it, I think).

By examining a magnetic field, you cannot tell whether its source was a
displacement or charge current (a frame dependent measurement and
assignment).

-Bob

*the only criterion for any physics.

Bob Sciamanda
Physics, Edinboro Univ of PA (ret)
trebor@velocity.net
http://www.velocity.net/~trebor