Calculating Power and Voltage Drops in an Electric Circuit

[lazypast]

Homework Statement

the questions quite big, but ill stick to the relevant parts

power at the load, 35000W
Voltage at load, 220V

cable resistance = 0.1ohm
field resistance = 60V

The Attempt at a Solution

the current at the load is P (load)/ V (load) = 35000/220 = 159A

the voltage drop from resistance, IR = 159x0.1 = 15.9V
terminal voltage is 15.9 + 220 = 235.9V

and so across the inductor - current (field) = V/R(field) = 235.9/60 = 3.93A

so now at this point, it asks for the armature current. which is calculated to be
159A + 3.93A = 163A

so here the current in armature is 163A yet the current at the load is 159A
there is only 1 cable the current can travel down, and to me it can either be 1 or the other.

can someone please explain any of this. any help greatly appreciated.

(by the way, these are the values calculated by my lecturer. he would give 100% on if you answered with these values)

 

[AvroArrow]

The answer is actually quite simple. The 159A that is calculated is the current at the load, not the current in the armature. The current in the armature (163A in this case) is the sum of the current at the load and the current through the field resistance. The cable resistance is also taken into account when calculating the voltage drop across the load. So in this case, 159A is the current at the load, and 163A is the current in the armature.

 

[Moetasim]

I would first like to commend the student for their attempt at solving the problem and for seeking clarification on any discrepancies in their calculations. It is important to question and understand the reasoning behind any calculations in scientific experiments.

From my understanding, the discrepancy in the calculated armature current and the current at the load could be due to the fact that the circuit is not an ideal circuit and there may be some losses or inefficiencies in the system. In real-life applications, the actual current may differ slightly from the calculated values due to factors such as resistance in the wires, imperfect components, and other external factors.

Additionally, it is also important to consider the concept of Kirchhoff's laws, specifically Kirchhoff's current law which states that the sum of currents entering a node must equal the sum of currents leaving the node. In this case, the current at the load may not necessarily be the same as the current in the armature due to the presence of other components in the circuit.

In conclusion, while the calculated values may not exactly match the real-life values, it is important to understand the underlying principles and factors that may affect the results. As a scientist, it is crucial to continuously question and analyze the data to ensure accurate and reliable results.