Final answer:
In a 12V generator system with constant load current and RPM, the field current due to the voltage regulator stays constant.
Step-by-step explanation:
In a 12V generator system with constant load current and RPM, the field current due to the voltage regulator stays constant (option C). The voltage regulator is responsible for maintaining a steady voltage output from the generator by adjusting the field current.
When the load current and RPM remain constant, the field current needs to be kept constant to ensure a stable output voltage. If the field current were to decrease, the generator's output voltage would also decrease. Conversely, if the field current were to increase, the output voltage would increase. Therefore, the field current is regulated to stay constant in order to maintain a stable 12V output.
It's important to note that the power dissipated in the generator may vary based on the load current and RPM, but the field current is adjusted by the voltage regulator to keep the output voltage constant.