1. The problem statement, all variables and given/known data The circuit shown above consists of a single battery, whose emf is 1.4 V, and three wires made of the same material, but having different cross-sectional areas. Each thick wire has cross-sectional area 1.4e-6 m2, and is 21 cm long. The thin wire has cross-sectional area 6.4e-8 m2, and is 7.5 cm long. In this metal, the electron mobility is 6e-4 (m/s)/(V/m), and there are 8e+28 mobile electrons/m3. Use the appropriate equation(s), plus the equation relating electron current to electric field, to solve for the factor that goes in the blank below: EF = ? * ED Use the appropriate equation(s) to calculate the magnitude of ED ED = ? Use the appropriate equation(s) to calculate the electron current at location D in the steady state 2. Relevant equations ??? 3. The attempt at a solution Already tried it, and I can't do it. E = emf/L doesn't work here. I've looked everywhere to try and find equations that can help me solve it, or at least relate the thin and thick wire. My physics book seems to skip this whole section (I'm using a different physics book than my class, which kind of sux for me, but I didn't want to buy another one).