Final answer:
The question involves calculating parameters of a series-wound DC motor's operation, such as the resistance of the motor coils, back emf, and starting current, using laws like Ohm's Law and the power equation.
Step-by-step explanation:
The question is asking for the unknown parameters related to a series-wound DC motor's operation when connected to a particular voltage source. The resistance of the motor coils, the back electromotive force (emf), and the current drawn under various conditions are the specific aspects being investigated.
Electric Motor Basics
Essential to capturing the scenario outlined are a few fundamental laws of electrical engineering, such as Ohm's Law (V = IR) and the power equation (P = IV), which can be applied to a DC motor's circuit to solve for the missing variables.
Motor Characteristics
A back emf is generated by a motor as it spins, which opposes the supply voltage. This emf is zero when the motor is not running. At operating speed, the back emf nearly matches the driving voltage, and the motor draws minimal current, just enough to overcome losses like friction.
When the motor starts, no back emf exists, and it draws more current due to the full supply voltage being applied across the total resistance of the armature and field coils. The starting current is determined by using the total resistance and the supply voltage.