(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known dataWhat is the magnitude and direction of the current in the following circuit?

[URL=http://imageshack.us][PLAIN]http://img234.imageshack.us/img234/7587/circuituk2.gif[/URL][/PLAIN]

resistance for series: Req=R1+R2+R3+R4....etc

Kirchhoff's rules --> Loop Rule: sum of potential drops must equal sum of potential rises

V=IR

3. The attempt at a solution

1st added all the voltage drops: I(5+27+12+8) = I52

2nd added all the Voltage rises: 30 + 10 = 40V

3rd solved for V when V=IR

40 volts/52 ohms= I

*since resistors are in series they experience the same current right?

my answer.77 Amps clockwise [which is wrong] the right answer is .38 Amps clockwise

My question is this: Why am i not supposed to add the voltages (30+10) together when solving this problem??If i solve for this problem in the following way, 30V-10V = I(52ohms) then i get .38 Amps clockwise (which is right) but i don't understand why i have to subtract the voltages!

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# Voltage in a 2 battery series circuit

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