For the circuit shown in the figure below, calculate
the current I4 through the 2.18 resistor. As shown,
R1 = 4.20
R2 = 8.12
R3 = 6.10
R4 = 2.18
I1 = 3.16A and E1 = 18V
I couldnt get the picture on here but I will describe it:
It is a parallel circuit, with three lines from top to bottom,
on the top line from left to right is R1 (with I1 pointing right) and R2
on the middle line is R3 and E1 (battery) (from left to right it is + to -)
on the bottom line is E2 (unknown voltage, and is + to - from right to left) and R4 (with I4 pointing left).
The Attempt at a Solution
I determined 2 loop equations,
for the upper loop I thought that R1 and R2 would have the same current being in series so, i have: -I1R1-I1R2+18V+I3R3=0
and for the lower loop I have -I3R3-18V-I4R4+E2=0
For the first loop equation I solved for I3=3.43A then I thought (just a guess) that each line would add up to the same total voltage in relation to each other line. The upper two lines both came out to 38.9V so I thought I was right in guessing that. So I figured E2+I4R4=38.9V also.
So I used my -I3R3-18V-I4R4+E2=0 equation and substituted the E2 for 38.9V-I4R4 and solved for I4. It came out very close to zero, -.005275A to be exact. Does this seem right?