A uniform metal wire of length and radius carries a steady current
PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity
Problem
A uniform metal wire of length L and radius r carries a steady current I. The wire is now drawn so that its length becomes 2L while its volume remains constant. Throughout the stretching process the temperature, free–electron density and the current I are unchanged.
(i) Show that the drift velocity of electrons in the stretched wire is twice the initial drift velocity.
(ii) Obtain the ratio of the final resistance of the wire to its initial resistance.
(iii) How does the magnitude of the electric field inside the wire change as a result of stretching? Justify your answer mathematically.