Why isn't this right? Finding the Va-Vb, kirchofs rule

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SUMMARY

The discussion centers on calculating the potential difference Va - Vb using Kirchhoff's rules in a circuit with resistances R1 = 1 ohm, R2 = 2.2 ohms, and ideal batteries with emfs E1 = 2.0 V and E2 = 3.0 V. The user correctly calculated the currents through each battery as -0.328125 A, 0.15625 A, and 0.171875 A but incorrectly determined the potential difference Va - Vb as 3.34 V. The error in the potential difference calculation indicates a misunderstanding of the application of Kirchhoff's voltage law in the circuit.

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mr_coffee
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Hello everyone, this seems easy enough...but i missed it!
Here is the drawing and here is my work:
http://img203.imageshack.us/img203/3928/lastscan7qe.jpg
In Figure 27-40, the resistances are R1 = 1 , R2 = 2.2 , and the ideal batteries have emfs E1 = 2.0 V, and E2 = 3 = 3 V.
http://www.webassign.net/hrw/hrw7_27-40.gifFig. 27-40

(a) What is the current through each battery? (Take upward to be positive.)
Battery 1: -.328125
Battery 2: .15625
Battery 3: .171875
I found all these and got them right.

What is the potential difference Va - Vb?
3.34 <-- wrong

How did i mess up ? Thanks
 
Last edited by a moderator:
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N/m i got it!
 

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