MicroVAX II

From: Dave Woodman <dave_at_naffnet.org.uk>
Date: Sun Nov 24 07:50:01 2002

Peter Turnbull wrote:

> On Nov 24, 10:14, Dave Woodman wrote:
>
> > Let's try to keep this in accordance with real physical laws:- the
> > current flowing in the wires will be inversely proportional to the
> > resistance since the potential difference across them is the same.
>
> So far, so good...
>
> > The physical principle
> > that causes the problem is that the power dissipated is proportional to
> the *square* of the current. In case of any doubters -
> >
> >
> > Ohms Law:
> > I = V/R
> >
> > => V=IR
> >
> > Power dissipated:
> > P = IV
> >
> > => P = I(IR)
> >
> > So, for example, if one cable/connector pair had twice the resistance of
> > another, the second would dissipate four times as much power as the
> > first.
>
> Er, no. The current will NOT be the same in each case. If you're going to
> use mathematical equations to argue, use the right ones :-)

I did not mean to imply that the current is the same, merely to illustrate
that
the power dissipated is proportional to the square of the current! I therefore

stand by what I wrote, for the purposes that I wrote it only.

Your posting does indeed, better analyse the situation, but I was not
attempting
to do that.

The reason that I felt it necessary to post was the assertion that 'current
always
uses the way of lowest resistance' which would imply that the user could have
only one set of cables - and a real fire would be soon on the cards.

    Cheers,

            Dave.
Received on Sun Nov 24 2002 - 07:50:01 GMT