Homework Help: Power delivered to each source. Image included

1. Jul 18, 2016

Josh225

1. The problem statement, all variables and given/known data
I got the correct answers for A and B, I just need help with C and D.

A. Find indicated currents. I1= I2 = 3 A ... IL = 6 A

B. Find total power delivered by each source. PE = 12 V (3A)

C. Find the total power delivered by each source and compare it to the power delivered to the load RL.

D. If only source current was available, what would the current drain be to supply the same power to the load? How does the current level compare to the calculated level of part A.
2. Relevant equations
PE = E Is

Is = E/ RT
3. The attempt at a solution
A. Find indicated currents. I1= I2 = 3 A ... IL = 6 A

B. Find total power delivered by each source. PE = 12 V (3A)

C. It says the answer is 72 W, but im unsure how to get there. I figured that I would find RL by applying ohms law (R= V/I ... R=12/3 = 4 ohms) then subtracting it from PL (72 W), but that gets me the wrong answer.

D. For D, I am not so sure..

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2. Jul 18, 2016

andrewkirk

C is a question (find the power) followed by an instruction (to make a comparison). The question part looks identical to question B, other than an apparently unimportant 'the'. Are you sure you have typed in the questions correctly?

Also, if we are told that 72W is being dissipated in the resistance, doesn't the symmetry between the two batteries in the circuit dictate that each must be supplying half of that power, without having to do any calculations?