One way a multiple-speed ventilation fan for a car can be designed is to put resistors in series with the fan motor. The resistors reduce the current through the motor and make it run more slowly. Suppose the current in the motor is 5.0 A when it is connected directly across a 12-V battery.
(a) What series resistor should be used to reduce the current to 2.0 A for low-speed operation?
(b) What power rating should the resistor have? Assume that the motor's resistance is roughly the same at all speeds.