Yes, you did. And I agree. Although I think I understand more clearly now
and can rephrase the idea we both agree with so it says this:

given two bulbs that produce the same desired lumen output at one foot from
the bulb, the first bulb being a fist-sized incandescent and the second
being a 4 foot long tube, the difference in the size of the lumen footprint
between the two bulbs is what makes one more desirable than the other. The
first bulb produces a 1 foot by 1 foot space of desired lumens, the second
produces a 1 by 4 foot space of desired lumens.

However, what really through me for a few minutes in what I read he

HOWEVER, from a large or diffuse source such as a fluorescent tube,
the falloff is less drastic because the tube is, in effect, a large
number of overlapping point sources. The handy rule for such a source
is that the intensity falls off as the inverse of the distance, i.e.
twice as far ,1/2 as intense, three times as far, 1/3, etc.

was the difference between "inverse" and "inverse square". One makes the
statement false; although not so far wrong in the short distances we are
talking about under a bulb, that it was worth jumping to this lovely thread.
The other thing that threw me was the need to state how distance and
intensity are related in the equation. "Twice" and "Three times" mislead
me, (again the distances we are talking about are small, so as a handy rule
over distances of a foot or two, it works well enough). Anyway, I managed
to puzzle out the paragraph and make sense of it to my own satisfaction.
Sorry to do it in front of everybody, I should have just roamed around the
greenhouse talking to myself until I figured it out. That would have been
the more peaceable choice.

This is an interesting thread. Don't stop on my account.



sizein the 600 lumen footprint located at one foot from the bulb. ban
encandecent bulbcandesnt bulb and a that with a incasent bulb, that the
difference between a florecent and inThere is a difference between inverse
and inverse square.
"jadel" wrote in message
ups.com...
On Sep 26, 6:29 pm, "Al" wrote:
it always falls off at the same rate. The difference is a florescent
tube
is long and narrow, so the 'point' of light is really many points of
light.

Which is what I said.

J. Del Col