- #1

- 57

- 0

## Homework Statement

What 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

## 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!