Prev: To find out why QUARKS have assymptotic freedom
Next: DON'T GET TOO MUCH BULLSHIT ON YOUR SHOES
From: Paul B. Andersen on 6 Jan 2010 10:20
On 06.01.2010 00:02, DSeppala wrote:
> The setup
> Let there be two identical electronic circuits on the x-axis. Let one
> be positioned at x = -L and the other at x = L. Each circuit consists
> of a resistor and capacitor in parallel, and a power supply applying
> voltage V across the resistor and capacitor. A wire connects the
> grounds of the two circuits together, and two identical resistors in
> series connect the charged side of the two circuits together, with the
> two series resistors meeting at an ammeter at x = 0.
>
> The experiment
> Prior to the start of the experiment, each power supply has reached a
> steady-state voltage of V, and the ammeter at x=0 reads zero current
> flow through the two series resistors. At time t0, observers in a
> frame moving with velocity along the x-axis, simultaneously (as
> measured in their frame) disconnect the power supply from both
> circuits. As measured in the rest frame of the setup, one power
> supply was removed from one circuit before the power supply was
> removed from the other circuit. This causes the ammeter at x = 0 to
> read a non-zero value.

But this will happen a time > L/c later. And the reading will be
non-zero for a very short time, namely 2Lv/c^2. (which is < L/c)

> The experiment is repeated with the power
> supply voltages reversed so that current flows in the opposite
> direction thru the series resistors when the power supplies are
> sequentially removed.

Which will change nothing (but the sign of the reading).

> How do the moving frame observers explain the ammeter reading a non-
> zero value

Note that the very brief non zero reading will happen after a delay
which is much greater than the duration of the non-zero reading.

The observer will find it quite reasonable that the information
"front supply removed" will reach the ammeter before the information
"aft supply removed" reaches it.
The information is moving with the speed of light (or slower)
in the moving observer's frame, and the ammeter is meeting
the approaching information from the "front supply", and receding
from the other.


> when these same observers also measure the difference in
> voltage across the series resistors to always be zero,

Not true. (But practically impossible to measure.)

> and occurring
> in an identical fashion independent of the direction of current flow
> when the voltage is reversed in the second experiment?

Why should the direction of the current matter?

In a wire, say 1mm^2 1A, the average speed of the electrons
is a few millimetres per second.
You don't think the current is reversed relative to you if you
walk along the wire in the same direction as the electrons
are moving, do you? :-)

Point being: The current in a wire is given by the relative
speed between the positive and negative charges.


--
Paul

http://home.c2i.net/pb_andersen/
First  |  Prev  | 
Pages: 1 2 3
Prev: To find out why QUARKS have assymptotic freedom
Next: DON'T GET TOO MUCH BULLSHIT ON YOUR SHOES