A permanent-magnet automotive fan motor draws 20 A from a 12-V source when the rotor is locked (i.e., held motionless).
a. Find the armature resistance.
b. Find the maximum developed power that this motor can produce when operated from a 12-V source.
c. Repeat part (b) for operation at 10V (this represents a nearly dead battery) and at 14V (this is the terminal voltage during charging of the battery after the engine is started).