Suppose that wire a and wire b are made of different metals and are subjected to the same electric field in two different circuits. wire b has 7 times the cross-sectional area, 2.8 times as many mobile electrons per cubic centimeter, and 5 times the mobility of wire a. in the steady state, 2 ✕ 10^18 electrons enter wire a every second. how many electrons enter wire b every second?

Consider a production line with five stations. station 1 can produce a unit in 9 minutes. station 2 can produce a unit in 10 minutes. station 3 has two identical machines, each of which can process a unit in 12 minutes (each unit only needs to be processed on one of the two machines. station 4 can produce a unit in 5 minutes. station 5 can produce a unit in 8 minutes. which station is the bottleneck station?