A copper wire of radius 1.00 mm and length 2.00 m is gently stretched
PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
A copper wire of radius 1.00 mm and length 2.00 m is gently stretched, at constant volume and constant temperature, until its length becomes 4.00 m.
(a) Derive an expression for the new radius r2 in terms of the original radius r1 and the original and final lengths.
(b) Determine the numerical value of the new radius after stretching.
(c) Calculate the percentage change in the wire’s electrical resistance as a result of the stretching process.
(d) Briefly explain, in terms of charge-carrier motion, why stretching the wire affects its resistance even though the microscopic resistivity of the copper remains unchanged.