- #1
roinujo1
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Homework Statement
In the circuit shown, what must be the size of the resistor R such that the power delivered to the 8 Ω resistoris 160 Watts?
Circuit is in the first image
Homework Equations
- ∑I at Junction= 0
- ∑ΔV though loop=0
- P=I2R
- ΔV=ε-Ir
The Attempt at a Solution
The circuit I have drawn is in the second image. The first thing I did was found the current that is going through R1 is 4.47 A. Since R1 and R2 are in series, I thought that they had the same resistance as well. Next, I used the first part of Kirchoff's law to find the junction equations:
- Junction B: I1= I2+ I3
- Junction E=I4 +I6=I5
- Loop AFEBA: -ε1+ R1I5+R2I5+R3I6-ε2+rI6+R4I2=0
- Note, that for the ε2, there is a internal resistance within the battery, such that the ΔV=ε-Ir. I think that the I would be equal to the one in the unknown resistor, I6.
- Loop EDCBE: -ε3+R5I3-R4I2+ε2-I6r -R3I6=0
- Loop ACDFA: -R5I3 +ε3-R2I5-R1I5+ε1=0
Also, I am not completely sure with the circuit I have drawn the currents are all correct the way I have drawn them.
Any help will be much appreciated.