Date: Mon, 27 Jul 98 08:28:00 -0600 From: robert.pogson@mwcs.mb.ca (ROBERT POGSON) To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2485$foo@default> Subject: Re: My Terrarium
"steve gordon" <gordon@rapid.co.uk> wrote:
C>
C> Another thing you need to consider is the distance from the light.
C> Artificial light is subject to what is know as the 'Inverse Square Law ';
C> this law of physics says that the light energy available is in inverse
C> proportion to the distance it has travelled or to put it in layman's terms
C>[and that includes me ] if you double the distance of an object from a light
C> source you will quarter the amout of light received, if it is four times
C> away it receives a sixteenth and so on.
There is a way to get around the 1/r^2 thing. Use an extended light source.
If you have an infinite sheet of light, the intensity will be constant with
distance. It's like Safeway, the light at the top shelf and bottom is the
same because the light source is extended. In practical terms, rows of
fluorescent tubes shoulder to shoulder will give good intensity further
away. The intensity will depend on the number of tubes per unit length and
their brightness.
Near the edges, the light still drops off so you need an array wider
than your plant space. This technique allows room to smell the roses or
to peek into traps. Another approach is to suspend the array of tubes by
a rope and pulley arrangement (at least 3 ropes in a triangular arrangement
for stability) to permit closeness or working height to be varied.
... nfx v2.8 [C0000] Physics is phun!
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