A cylindrical metallic wire of initial length L and radius r has resistance R
PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
A cylindrical metallic wire of initial length L and radius r has resistance R. The wire is now drawn uniformly so that its length becomes kL (k>1) while its volume remains constant.
(i) Derive an expression for the new resistance R' of the stretched wire in terms of the original resistance R and the stretching factor k.
(ii) From your result, explain why the resistivity of the material remains unchanged although the resistance has altered.
(iii) State, with reasoning, whether the mobility of the charge carriers in the wire is affected by the mechanical drawing process described above.