A uniform copper wire of length L and resistance R0 is stretched, without loss of material, to double its original length.
(i) Show that its new resistance R becomes four times R0.
(ii) A constant potential difference is applied between the ends of the wire before and after stretching. Derive the ratio of the new current to the original current.
(iii) The original wire has length 1.0m and resistance 3.0Ω. It is stretched to 2.0m. Calculate the current through the wire when 9.0V is applied (a) before stretching and (b) after stretching.