Assignment:
Thin Manganin wire of the length l = 0.5 m is glued to the electrically insulating rod. The insulating rod is subsequently stretched by applying axial mechanical force. Prior to stretching the resistance of Manganin wire was R0 = 10 ? and after applying the axial force R1 = 10.01 ?.
Determine:
a) Diameter of the wire D when no mechanical force is applied;
b) Relative length change of the insulating rod Δl / l [%]
Note:
1) Assume no relative movement between the wire and insulating rod;
2) Electrical resistivity change due to stretching can be neglected;
3) Relative deformations in axial and transverse dimensions of the wire are satisfying the Poisson's ratio which is µ=0.35.
4) Electrical resistivity of Manganin is ρ = 43·10-8 ?m.