Dumet wire was developed to allow for the expansion of glass in lightbulbs. The wire consists of a core of nickel – steel (invar ) surrounded by a sheath of copper. The diameter of the core and of the sheath are chosen so that the wire duplicates the expansion characteristics of glass. (a) show that the ratio of the nickel –steel radius to that of the copper sheath should be.

Radhika Batra , 9 Years ago

Grade 11