1. The problem statement, all variables and given/known data A x cm long wire has a diameter of y mm and a resistivity of 4.0x10-7 ohm-cm. Calculate its resistance. 2. Relevant equations R = p*L/A 3. The attempt at a solution First, I convert the given information into SI units: Length = x*10^-2 m Diameter = y*10^-3 m Resistivity = 4*10^-5 ohm/m Next, cross-sectional area of a wire/cylinder is pi*r^2 = pi*(d/2)^2 = (1/4)pi*d^2 R = p*L/A = p*L/((1/4)pi*d^2) = (4 L p)/(d^2 pi) If x = 20 cm and y = 0.3mm, R = (4*20*10^-2 *4*10^-5)/((0.3*10^-3)^2*Pi) = 113.177 ohms Is this correct? My TA told me that I converted the units wrongly, and that the correct answer is 0.0113177 ohms.