A while back, there was a discussion on Orchid Re: Halogen lamps. I
just discovered a website with a great explanation of the way they
work.
http://www.goodmart.com/facts/light_bulbs/halogen_diagram.aspx
David Barzilay
Lord of the Rings
607 S Hill St Ste 850
Los Angeles, CA 90014-1718
213-488-9157