A copper wire of original length and cross-sectional area has resistance
PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
A copper wire of original length l and cross-sectional area A has resistance R. The wire is then stretched carefully so that its length becomes 2l while no material is lost.
(i) State the mathematical relation that connects the resistance of a uniform conductor with its length and cross-sectional area.
(ii) Keeping the volume of the wire constant, explain qualitatively how its cross-sectional area changes when the length is doubled.
(iii) Using appropriate reasoning, state whether the resistivity of the material changes during the stretching process. Give a brief justification.