A dc motor with split ring commutator and magnet is used to drive a robot car it has a 9V dc power supply. In a experiment it is powered on and the current is measured against time while the shaft is resisted by hand to act a high load.

i).Why did it take some time for the current to go to its ultimate value? ii).if you analyse this picture what would the 2 component vals for coil-windings be? iii). How would it affect the performance of the robot car? iv). The measurement is repeated the motor is now rotating quickly, the ultimate value is lower than before - why is that?

current 3.5 A vs T (amps) 3 2.5 2 1.5 1 0.5 0 0 1000 2000 3000 4000 5000 time miliseconds current 3.5 A vs T (amps) 3 2.5 2 1.5 1 0.5 0 0 1000 2000 3000 4000 5000 time miliseconds