Respectfully disagree, and I earlier posited that it was energy per unit length
of the bolt. In electrical and magnetic fields, line sources are frequently
assumed as an approximation. Of course, real sources would tend to have a
diameter, but for distances large compared to diameter, but small compared to
length, a line source is a convenient approximation. You can then go on to
determine the energy stored in space around the line source or power radiated
from it and it will have dimensions of J/m, W/m or for long florescent tubes,
lumens per meter.
Now I will admit that lightning bolts aren't very straight and the usefulness
of this measure in this situation isn't very apparent to me. However, I can
think of cases where it is very useful, long, straight wires, lighting, etc.
From: Stanislav Jakuba <[email protected]>
To: Bill Hooper <[email protected]>; U.S. Metric Association
<[email protected]>
Sent: Tuesday, August 9, 2016 9:49 AM
Subject: [USMA 291] Re: Puzzled
MJ/m:Well, I guess, there will not be the consensus. My take: The unit J/m
refers to a non-existing quantity and for that and other reasons it cannot
exist. The quantity "length" cannot have energy, be it in mm, m, or Mm. Nor can
an area (m2) contain energy. The sensible units are: energy per volume (J/m3),
or energy per mass (J/kg), and, of course, energy per time which we call the
watt (W).
The question is - how seriously should we take a scientific information that
repeatedly refers to a non-existing SI unit? What more can USMA do to help out
scientist get SI literate? Particularly governmental as has been the case here.
Stan
On Sat, Aug 6, 2016 at 11:57 AM, Bill Hooper <[email protected]> wrote:
On my iPad from Cypress Village, Jacksonville, FL
On Aug 5, 2016, at 12:08 PM, Stanislav Jakuba <[email protected]> wrote:
>
> Once more: What is J/m?
> How about reaching a consensus? ☺
> Stan
>
I think the "m" in "J/m" refers to the length of the lightning stroke . It
measures the energy of each meter of length of the stroke. It's joules of
energy per meter of length of the stroke.
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