Chapter 27, Problem 16P

You have a faculty position at a community college and are teaching a class in automotive technology. You are deep in a discussion of using jumper cables to start a car with a dead battery from a car with a fresh battery. You have drawn the circuit diagram in Figure P27.16 to explain the process. The battery on the left is the live battery in the correctly functioning car, with emf ε and internal resistance R_L, where the L subscript refers to “live.” Its terminals are connected directly across those of the dead battery, in the middle of the diagram, with emf ε and internal resistance R_D, where the D subscript refers to “dead.” Then, the starter in the car with the dead battery is activated by closing the ignition switch, allowing the car to start. The resistance of the starter is R_S. A student raises his hand and asks, “So is the dead battery being charged while the starter is operating?” How do you respond?

Figure P27.16