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In reviewing mail for deletion I read the below and think JC's question
was not answered (I read the thread, but not carefully.)
"Perhaps they put out more light in the more visible portion of the
spectrum to validate the claim of higher efficiency?"
Many optics books (especially if written for engineers) begin with
concepts in radiometry and photometry -- defining their corresponding
units, etc. the difference is visual. photometry refers to light (that
portion of the EM spectrum the std. observer "sees") while radiometry is
limited to the region defined under discussion. e.g. the total
radiation from a given source. Therefore, since the lumen is a
photometric unit, luminous efficiency already takes into account the
energy in the visible and its stimulus of the std. observer.
John Clement wrote:
That may be true, but the tag actually implied you were saving
electricity. It did not have any information about lifetime or bulb
cost. It looked so impressive until you read the actual information.
What surprised me is that 60W halogen bulbs have comparable rated light
output to 60W regular bulbs the last time I looked at them in the store.
They usually have some claims about being "more efficient". Perhaps
they put out more light in the more visible portion of the spectrum to
validate the claim of higher efficiency?
Things have not changed since they sold in radio ads genuine 14 carat
simulated gold rings.
John M. Clement
From: Forum for Physics Educators [mailto:PHYS-L@lists.nau.edu] On
Of Tim Folkerts
Sent: Saturday, June 21, 2003 3:32 PM
Subject: Re: Season misconceptions in newspaper