Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!think.com!snorkelwacker.mit.edu!bloom-beacon!bloom-beacon!eru!hagbard!sunic!isgate!krafla!adamd From: chuck@marie.mit.edu (PARSONS, CHARLES) Newsgroups: sci.electronics Subject: Re: Do Halogen lamps need ballasts? Message-ID: <1990Dec3.162603.2980@athena.mit.edu> Date: 3 Dec 90 17:21:33 GMT References: <714@skipper.dfrf.nasa.gov> <1147@inews.intel.com> <1990Dec1.032426@envy.bellcore.com> <1197@inews.intel.com> <36440@cup.porta Sender: daemon@athena.mit.edu (Mr Background) Reply-To: chuck@marie.mit.edu Organization: MIT - Lab for Nuclear Science Lines: 23 In article <2473@krafla.rhi.hi.is>, adamd@rhi.hi.is (Adam David) writes... >In <36440@cup.portal.com> metzger@cup.portal.com (David G Metzger) writes: > >>In article <1197@inews.intel.com>, bhoughto@cmdnfs.intel.com >> (Blair P. Houghton) writes: >>>(cleaving). When there's a uniformity of heat >> ^^^^^^^^ > >> Quartz does not have cleavage planes. When quartz breaks, it >>is by conchoidal fracture. > >Depends on how it grew doesn't it? Defects in the crystal can form very regular >fracture planes that behave just like cleavage planes. This weak area is the one >most likely to break if the deformation occurs nearby. But then again, there >aren't supposed to be any defects are there? > "Quartz" halogen light tubes are not Crystals they are amorphous. The quartz label just refers to the fact that the glass is almost pure SiO2 without the usual salts added to window glass to lower the melting point. Chuck@mitlns.mit.edu Brought to you by Super Global Mega Corp .com