(a) Find the resistance between two opposite edge faces of a piece of square carbon film of thickness 5.0 x 10^-7 n,if the resistivity of carbon is 4.0 x 10^-5 ohm meter. (b) A carbon film of the same thickness is formed on an insulator rod of diameter 3.0m.What is the length of the rod so that the carbon film on its curve surface has a resistance of 100 ohm ? Question (a) and (b) is continuous and I have no problem with question (a).My problem is question (b) and I can't really understand with the question and I can't imagine out the figure. I want to ask whether there is any relationship of answers in question (a) in solving the qiestion (b) and I really need someone to explain to me the phrase 'curve surface' . Thanks for anybody that spend some time on this question and I really need explaination for this question.