To tolerate high operating temperatures, which of the following has to be done in incandescent or tungsten filament lamps?
(a) Alloys must be used
(b) Nitrogen be used instead of inert gas
(c) Envelope is fabricated with quartz
(d) Envelope is fabricated with copper
The question was asked in an international level competition.
My query is from Absorption Instrumentation and Block Diagram Representation topic in portion Colorimetry and Spectrometry of Analytical Instrumentation